diff --git a/Marlin/Configuration_adv.h b/Marlin/Configuration_adv.h
index 726058ebbc..7b642cc355 100644
--- a/Marlin/Configuration_adv.h
+++ b/Marlin/Configuration_adv.h
@@ -532,6 +532,11 @@
   //#define USE_OCR2A_AS_TOP
 #endif
 
+/**
+ * Use one of the PWM fans as a redundant part-cooling fan
+ */
+//#define REDUNDANT_PART_COOLING_FAN 2  // Index of the fan to sync with FAN 0.
+
 // @section extruder
 
 /**
@@ -677,6 +682,12 @@
   #endif
 #endif
 
+// Drive the E axis with two synchronized steppers
+//#define E_DUAL_STEPPER_DRIVERS
+#if ENABLED(E_DUAL_STEPPER_DRIVERS)
+  //#define INVERT_E1_VS_E0_DIR   // Enable if the E motors need opposite DIR states
+#endif
+
 /**
  * Dual X Carriage
  *
diff --git a/Marlin/src/MarlinCore.cpp b/Marlin/src/MarlinCore.cpp
index 78c97cf3a3..404f36c79f 100644
--- a/Marlin/src/MarlinCore.cpp
+++ b/Marlin/src/MarlinCore.cpp
@@ -421,19 +421,18 @@ void startOrResumeJob() {
  *  - Check if an idle but hot extruder needs filament extruded (EXTRUDER_RUNOUT_PREVENT)
  *  - Pulse FET_SAFETY_PIN if it exists
  */
-inline void manage_inactivity(const bool ignore_stepper_queue=false) {
+inline void manage_inactivity(const bool no_stepper_sleep=false) {
 
   queue.get_available_commands();
 
   const millis_t ms = millis();
 
-  // Prevent steppers timing-out in the middle of M600
-  // unless PAUSE_PARK_NO_STEPPER_TIMEOUT is disabled
-  const bool parked_or_ignoring = ignore_stepper_queue
+  // Prevent steppers timing-out
+  const bool do_reset_timeout = no_stepper_sleep
                                || TERN0(PAUSE_PARK_NO_STEPPER_TIMEOUT, did_pause_print);
 
   // Reset both the M18/M84 activity timeout and the M85 max 'kill' timeout
-  if (parked_or_ignoring) gcode.reset_stepper_timeout(ms);
+  if (do_reset_timeout) gcode.reset_stepper_timeout(ms);
 
   if (gcode.stepper_max_timed_out(ms)) {
     SERIAL_ERROR_MSG(STR_KILL_INACTIVE_TIME, parser.command_ptr);
@@ -449,7 +448,7 @@ inline void manage_inactivity(const bool ignore_stepper_queue=false) {
     // activity timeout and the M85 max 'kill' timeout
     if (planner.has_blocks_queued())
       gcode.reset_stepper_timeout(ms);
-    else if (!parked_or_ignoring && gcode.stepper_inactive_timeout()) {
+    else if (!do_reset_timeout && gcode.stepper_inactive_timeout()) {
       if (!already_shutdown_steppers) {
         already_shutdown_steppers = true;  // L6470 SPI will consume 99% of free time without this
 
@@ -732,14 +731,14 @@ inline void manage_inactivity(const bool ignore_stepper_queue=false) {
  *  - Update the Průša MMU2
  *  - Handle Joystick jogging
  */
-void idle(TERN_(ADVANCED_PAUSE_FEATURE, bool no_stepper_sleep/*=false*/)) {
+void idle(bool no_stepper_sleep/*=false*/) {
   #if ENABLED(MARLIN_DEV_MODE)
     static uint16_t idle_depth = 0;
     if (++idle_depth > 5) SERIAL_ECHOLNPAIR("idle() call depth: ", idle_depth);
   #endif
 
   // Core Marlin activities
-  manage_inactivity(TERN_(ADVANCED_PAUSE_FEATURE, no_stepper_sleep));
+  manage_inactivity(no_stepper_sleep);
 
   // Manage Heaters (and Watchdog)
   thermalManager.manage_heater();
diff --git a/Marlin/src/MarlinCore.h b/Marlin/src/MarlinCore.h
index ce1b106bfa..01a1be4d59 100644
--- a/Marlin/src/MarlinCore.h
+++ b/Marlin/src/MarlinCore.h
@@ -34,8 +34,8 @@
 void stop();
 
 // Pass true to keep steppers from timing out
-void idle(TERN_(ADVANCED_PAUSE_FEATURE, bool no_stepper_sleep=false));
-inline void idle_no_sleep() { idle(TERN_(ADVANCED_PAUSE_FEATURE, true)); }
+void idle(bool no_stepper_sleep=false);
+inline void idle_no_sleep() { idle(true); }
 
 #if ENABLED(G38_PROBE_TARGET)
   extern uint8_t G38_move;          // Flag to tell the ISR that G38 is in progress, and the type
diff --git a/Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp b/Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp
index 11c05f6054..e144390c8d 100644
--- a/Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp
+++ b/Marlin/src/feature/bedlevel/ubl/ubl_G29.cpp
@@ -1025,7 +1025,7 @@ void set_message_with_feedback(PGM_P const msg_P) {
       SET_SOFT_ENDSTOP_LOOSE(true);
 
       do {
-        idle();
+        idle_no_sleep();
         new_z = ui.ubl_mesh_value();
         TERN_(UBL_MESH_EDIT_MOVES_Z, do_blocking_move_to_z(h_offset + new_z)); // Move the nozzle as the point is edited
         SERIAL_FLUSH();                                   // Prevent host M105 buffer overrun.
diff --git a/Marlin/src/feature/binary_stream.h b/Marlin/src/feature/binary_stream.h
index 9eb151b27f..2ad7f236a1 100644
--- a/Marlin/src/feature/binary_stream.h
+++ b/Marlin/src/feature/binary_stream.h
@@ -24,9 +24,11 @@
 #include "../inc/MarlinConfig.h"
 
 #define BINARY_STREAM_COMPRESSION
-
 #if ENABLED(BINARY_STREAM_COMPRESSION)
   #include "../libs/heatshrink/heatshrink_decoder.h"
+  // STM32 (and others?) require a word-aligned buffer for SD card transfers via DMA
+  static __attribute__((aligned(sizeof(size_t)))) uint8_t decode_buffer[512] = {};
+  static heatshrink_decoder hsd;
 #endif
 
 inline bool bs_serial_data_available(const serial_index_t index) {
@@ -37,16 +39,6 @@ inline int bs_read_serial(const serial_index_t index) {
   return SERIAL_IMPL.read(index);
 }
 
-#if ENABLED(BINARY_STREAM_COMPRESSION)
-  static heatshrink_decoder hsd;
-  #if BOTH(ARDUINO_ARCH_STM32F1, SDIO_SUPPORT)
-    // STM32 requires a word-aligned buffer for SD card transfers via DMA
-    static __attribute__((aligned(sizeof(size_t)))) uint8_t decode_buffer[512] = {};
-  #else
-    static uint8_t decode_buffer[512] = {};
-  #endif
-#endif
-
 class SDFileTransferProtocol  {
 private:
   struct Packet {
diff --git a/Marlin/src/gcode/bedlevel/G35.cpp b/Marlin/src/gcode/bedlevel/G35.cpp
index ad2cc67db0..44df6d9273 100644
--- a/Marlin/src/gcode/bedlevel/G35.cpp
+++ b/Marlin/src/gcode/bedlevel/G35.cpp
@@ -91,8 +91,8 @@ void GcodeSuite::G35() {
   // Disable duplication mode on homing
   TERN_(HAS_DUPLICATION_MODE, set_duplication_enabled(false));
 
-  // Home all before this procedure
-  home_all_axes();
+  // Home only Z axis when X and Y is trusted, otherwise all axes, if needed before this procedure
+  if (!all_axes_trusted()) process_subcommands_now_P(PSTR("G28Z"));
 
   bool err_break = false;
 
diff --git a/Marlin/src/gcode/calibrate/G34.cpp b/Marlin/src/gcode/calibrate/G34.cpp
index bcca00dd42..956960866d 100644
--- a/Marlin/src/gcode/calibrate/G34.cpp
+++ b/Marlin/src/gcode/calibrate/G34.cpp
@@ -39,7 +39,7 @@
 void GcodeSuite::G34() {
 
   // Home before the alignment procedure
-  if (!all_axes_trusted()) home_all_axes();
+  home_if_needed();
 
   TERN_(HAS_LEVELING, TEMPORARY_BED_LEVELING_STATE(false));
 
diff --git a/Marlin/src/gcode/calibrate/G34_M422.cpp b/Marlin/src/gcode/calibrate/G34_M422.cpp
index 1803933d16..6869962028 100644
--- a/Marlin/src/gcode/calibrate/G34_M422.cpp
+++ b/Marlin/src/gcode/calibrate/G34_M422.cpp
@@ -167,7 +167,7 @@ void GcodeSuite::G34() {
       ));
 
       // Home before the alignment procedure
-      if (!all_axes_trusted()) home_all_axes();
+      home_if_needed();
 
       // Move the Z coordinate realm towards the positive - dirty trick
       current_position.z += z_probe * 0.5f;
diff --git a/Marlin/src/gcode/feature/pause/M600.cpp b/Marlin/src/gcode/feature/pause/M600.cpp
index 2daa7d999a..541fa08350 100644
--- a/Marlin/src/gcode/feature/pause/M600.cpp
+++ b/Marlin/src/gcode/feature/pause/M600.cpp
@@ -99,7 +99,7 @@ void GcodeSuite::M600() {
 
   #if ENABLED(HOME_BEFORE_FILAMENT_CHANGE)
     // If needed, home before parking for filament change
-    if (!all_axes_trusted()) home_all_axes(true);
+    home_if_needed(true);
   #endif
 
   #if HAS_MULTI_EXTRUDER
diff --git a/Marlin/src/gcode/temp/M106_M107.cpp b/Marlin/src/gcode/temp/M106_M107.cpp
index dcb0d34ffe..3f85c53d78 100644
--- a/Marlin/src/gcode/temp/M106_M107.cpp
+++ b/Marlin/src/gcode/temp/M106_M107.cpp
@@ -60,39 +60,40 @@
  */
 void GcodeSuite::M106() {
   const uint8_t pfan = parser.byteval('P', _ALT_P);
+  if (pfan >= _CNT_P) return;
+  #if REDUNDANT_PART_COOLING_FAN
+    if (pfan == REDUNDANT_PART_COOLING_FAN) return;
+  #endif
 
-  if (pfan < _CNT_P) {
+  #if ENABLED(EXTRA_FAN_SPEED)
+    const uint16_t t = parser.intval('T');
+    if (t > 0) return thermalManager.set_temp_fan_speed(pfan, t);
+  #endif
 
-    #if ENABLED(EXTRA_FAN_SPEED)
-      const uint16_t t = parser.intval('T');
-      if (t > 0) return thermalManager.set_temp_fan_speed(pfan, t);
-    #endif
+  const uint16_t dspeed = parser.seen_test('A') ? thermalManager.fan_speed[active_extruder] : 255;
 
-    const uint16_t dspeed = parser.seen_test('A') ? thermalManager.fan_speed[active_extruder] : 255;
+  uint16_t speed = dspeed;
 
-    uint16_t speed = dspeed;
+  // Accept 'I' if temperature presets are defined
+  #if PREHEAT_COUNT
+    const bool got_preset = parser.seenval('I');
+    if (got_preset) speed = ui.material_preset[_MIN(parser.value_byte(), PREHEAT_COUNT - 1)].fan_speed;
+  #else
+    constexpr bool got_preset = false;
+  #endif
 
-    // Accept 'I' if temperature presets are defined
-    #if PREHEAT_COUNT
-      const bool got_preset = parser.seenval('I');
-      if (got_preset) speed = ui.material_preset[_MIN(parser.value_byte(), PREHEAT_COUNT - 1)].fan_speed;
-    #else
-      constexpr bool got_preset = false;
-    #endif
+  if (!got_preset && parser.seenval('S'))
+    speed = parser.value_ushort();
 
-    if (!got_preset && parser.seenval('S'))
-      speed = parser.value_ushort();
+  TERN_(FOAMCUTTER_XYUV, speed *= 2.55); // Get command in % of max heat
 
-    TERN_(FOAMCUTTER_XYUV, speed *= 2.55); // Get command in % of max heat
+  // Set speed, with constraint
+  thermalManager.set_fan_speed(pfan, speed);
 
-    // Set speed, with constraint
-    thermalManager.set_fan_speed(pfan, speed);
+  TERN_(LASER_SYNCHRONOUS_M106_M107, planner.buffer_sync_block(BLOCK_FLAG_SYNC_FANS));
 
-    TERN_(LASER_SYNCHRONOUS_M106_M107, planner.buffer_sync_block(BLOCK_FLAG_SYNC_FANS));
-
-    if (TERN0(DUAL_X_CARRIAGE, idex_is_duplicating()))  // pfan == 0 when duplicating
-      thermalManager.set_fan_speed(1 - pfan, speed);
-  }
+  if (TERN0(DUAL_X_CARRIAGE, idex_is_duplicating()))  // pfan == 0 when duplicating
+    thermalManager.set_fan_speed(1 - pfan, speed);
 }
 
 /**
@@ -101,6 +102,9 @@ void GcodeSuite::M106() {
 void GcodeSuite::M107() {
   const uint8_t pfan = parser.byteval('P', _ALT_P);
   if (pfan >= _CNT_P) return;
+  #if REDUNDANT_PART_COOLING_FAN
+    if (pfan == REDUNDANT_PART_COOLING_FAN) return;
+  #endif
 
   thermalManager.set_fan_speed(pfan, 0);
 
diff --git a/Marlin/src/inc/Conditionals_LCD.h b/Marlin/src/inc/Conditionals_LCD.h
index ea83b5abbc..833fe0d227 100644
--- a/Marlin/src/inc/Conditionals_LCD.h
+++ b/Marlin/src/inc/Conditionals_LCD.h
@@ -558,7 +558,12 @@
   #undef DISABLE_E
 #endif
 
-#if ENABLED(SWITCHING_EXTRUDER)   // One stepper for every two EXTRUDERS
+#if ENABLED(E_DUAL_STEPPER_DRIVERS) // E0/E1 steppers act in tandem as E0
+
+  #define E_STEPPERS      2
+
+#elif ENABLED(SWITCHING_EXTRUDER)   // One stepper for every two EXTRUDERS
+
   #if EXTRUDERS > 4
     #define E_STEPPERS    3
   #elif EXTRUDERS > 2
@@ -569,17 +574,24 @@
   #if DISABLED(SWITCHING_NOZZLE)
     #define HOTENDS       E_STEPPERS
   #endif
-#elif ENABLED(MIXING_EXTRUDER)
+
+#elif ENABLED(MIXING_EXTRUDER)      // Multiple feeds are mixed proportionally
+
   #define E_STEPPERS      MIXING_STEPPERS
   #define E_MANUAL        1
   #if MIXING_STEPPERS == 2
     #define HAS_DUAL_MIXING 1
   #endif
-#elif ENABLED(SWITCHING_TOOLHEAD)
+
+#elif ENABLED(SWITCHING_TOOLHEAD)   // Toolchanger
+
   #define E_STEPPERS      EXTRUDERS
   #define E_MANUAL        EXTRUDERS
-#elif HAS_PRUSA_MMU2
+
+#elif HAS_PRUSA_MMU2                // Průša Multi-Material Unit v2
+
   #define E_STEPPERS 1
+
 #endif
 
 // No inactive extruders with SWITCHING_NOZZLE or Průša MMU1
diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index ffb79a6baa..7a178db3aa 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -1161,6 +1161,19 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
   #endif
 #endif
 
+/**
+ * Dual E Steppers requirements
+ */
+#if ENABLED(E_DUAL_STEPPER_DRIVERS)
+  #if EXTRUDERS > 1
+    #error "E_DUAL_STEPPER_DRIVERS can only be used with EXTRUDERS set to 1."
+  #elif ENABLED(MIXING_EXTRUDER)
+    #error "E_DUAL_STEPPER_DRIVERS is incompatible with MIXING_EXTRUDER."
+  #elif ENABLED(SWITCHING_EXTRUDER)
+    #error "E_DUAL_STEPPER_DRIVERS is incompatible with SWITCHING_EXTRUDER."
+  #endif
+#endif
+
 /**
  * Linear Advance 1.5 - Check K value range
  */
@@ -1877,6 +1890,14 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
   #endif
 #endif
 
+#ifdef REDUNDANT_PART_COOLING_FAN
+  #if FAN_COUNT < 2
+    #error "REDUNDANT_PART_COOLING_FAN requires a board with at least two PWM fans."
+  #else
+    static_assert(WITHIN(REDUNDANT_PART_COOLING_FAN, 1, FAN_COUNT - 1), "REDUNDANT_PART_COOLING_FAN must be between 1 and " STRINGIFY(DECREMENT(FAN_COUNT)) ".");
+  #endif
+#endif
+
 /**
  * Case Light requirements
  */
diff --git a/Marlin/src/inc/Version.h b/Marlin/src/inc/Version.h
index cf6586f3f0..597ec2d553 100644
--- a/Marlin/src/inc/Version.h
+++ b/Marlin/src/inc/Version.h
@@ -42,7 +42,7 @@
  * version was tagged.
  */
 #ifndef STRING_DISTRIBUTION_DATE
-  #define STRING_DISTRIBUTION_DATE "2021-06-14"
+  #define STRING_DISTRIBUTION_DATE "2021-06-15"
 #endif
 
 /**
diff --git a/Marlin/src/lcd/menu/menu_temperature.cpp b/Marlin/src/lcd/menu/menu_temperature.cpp
index 33a3d2f445..96e6ee5f8e 100644
--- a/Marlin/src/lcd/menu/menu_temperature.cpp
+++ b/Marlin/src/lcd/menu/menu_temperature.cpp
@@ -57,8 +57,14 @@ void Temperature::lcd_preheat(const uint8_t e, const int8_t indh, const int8_t i
     if (indb >= 0 && ui.material_preset[indb].bed_temp > 0) setTargetBed(ui.material_preset[indb].bed_temp);
   #endif
   #if HAS_FAN
-    if (indh >= 0)
-      set_fan_speed(active_extruder < (FAN_COUNT) ? active_extruder : 0, ui.material_preset[indh].fan_speed);
+    if (indh >= 0) {
+      const uint8_t fan_index = active_extruder < (FAN_COUNT) ? active_extruder : 0;
+      if (true
+        #if REDUNDANT_PART_COOLING_FAN
+          && fan_index != REDUNDANT_PART_COOLING_FAN
+        #endif
+      ) set_fan_speed(fan_index, ui.material_preset[indh].fan_speed);
+    }
   #endif
   ui.return_to_status();
 }
@@ -215,37 +221,37 @@ void menu_temperature() {
     #if HAS_FAN0
       _FAN_EDIT_ITEMS(0,FIRST_FAN_SPEED);
     #endif
-    #if HAS_FAN1
+    #if HAS_FAN1 && REDUNDANT_PART_COOLING_FAN != 1
       FAN_EDIT_ITEMS(1);
     #elif SNFAN(1)
       singlenozzle_item(1);
     #endif
-    #if HAS_FAN2
+    #if HAS_FAN2 && REDUNDANT_PART_COOLING_FAN != 2
       FAN_EDIT_ITEMS(2);
     #elif SNFAN(2)
       singlenozzle_item(2);
     #endif
-    #if HAS_FAN3
+    #if HAS_FAN3 && REDUNDANT_PART_COOLING_FAN != 3
       FAN_EDIT_ITEMS(3);
     #elif SNFAN(3)
       singlenozzle_item(3);
     #endif
-    #if HAS_FAN4
+    #if HAS_FAN4 && REDUNDANT_PART_COOLING_FAN != 4
       FAN_EDIT_ITEMS(4);
     #elif SNFAN(4)
       singlenozzle_item(4);
     #endif
-    #if HAS_FAN5
+    #if HAS_FAN5 && REDUNDANT_PART_COOLING_FAN != 5
       FAN_EDIT_ITEMS(5);
     #elif SNFAN(5)
       singlenozzle_item(5);
     #endif
-    #if HAS_FAN6
+    #if HAS_FAN6 && REDUNDANT_PART_COOLING_FAN != 6
       FAN_EDIT_ITEMS(6);
     #elif SNFAN(6)
       singlenozzle_item(6);
     #endif
-    #if HAS_FAN7
+    #if HAS_FAN7 && REDUNDANT_PART_COOLING_FAN != 7
       FAN_EDIT_ITEMS(7);
     #elif SNFAN(7)
       singlenozzle_item(7);
diff --git a/Marlin/src/module/motion.cpp b/Marlin/src/module/motion.cpp
index d465a00356..b540c9a938 100644
--- a/Marlin/src/module/motion.cpp
+++ b/Marlin/src/module/motion.cpp
@@ -294,6 +294,10 @@ void report_current_position_projected() {
 
 #endif
 
+void home_if_needed(const bool keeplev/*=false*/) {
+  if (!all_axes_trusted()) gcode.home_all_axes(keeplev);
+}
+
 /**
  * Run out the planner buffer and re-sync the current
  * position from the last-updated stepper positions.
diff --git a/Marlin/src/module/motion.h b/Marlin/src/module/motion.h
index d099246f17..c41738a5ab 100644
--- a/Marlin/src/module/motion.h
+++ b/Marlin/src/module/motion.h
@@ -392,33 +392,35 @@ void set_axis_is_at_home(const AxisEnum axis);
   void set_axis_never_homed(const AxisEnum axis);
   linear_axis_bits_t axes_should_home(linear_axis_bits_t axis_bits=linear_bits);
   bool homing_needed_error(linear_axis_bits_t axis_bits=linear_bits);
-  FORCE_INLINE void set_axis_unhomed(const AxisEnum axis)   { CBI(axis_homed, axis); }
-  FORCE_INLINE void set_axis_untrusted(const AxisEnum axis) { CBI(axis_trusted, axis); }
-  FORCE_INLINE void set_all_unhomed()                       { axis_homed = axis_trusted = 0; }
-  FORCE_INLINE void set_axis_homed(const AxisEnum axis)     { SBI(axis_homed, axis); }
-  FORCE_INLINE void set_axis_trusted(const AxisEnum axis)   { SBI(axis_trusted, axis); }
-  FORCE_INLINE void set_all_homed()                         { axis_homed = axis_trusted = linear_bits; }
+  inline void set_axis_unhomed(const AxisEnum axis)   { CBI(axis_homed, axis); }
+  inline void set_axis_untrusted(const AxisEnum axis) { CBI(axis_trusted, axis); }
+  inline void set_all_unhomed()                       { axis_homed = axis_trusted = 0; }
+  inline void set_axis_homed(const AxisEnum axis)     { SBI(axis_homed, axis); }
+  inline void set_axis_trusted(const AxisEnum axis)   { SBI(axis_trusted, axis); }
+  inline void set_all_homed()                         { axis_homed = axis_trusted = linear_bits; }
 #else
   constexpr linear_axis_bits_t axis_homed = linear_bits, axis_trusted = linear_bits; // Zero-endstop machines are always homed and trusted
-  FORCE_INLINE void homeaxis(const AxisEnum axis)           {}
-  FORCE_INLINE void set_axis_never_homed(const AxisEnum)    {}
-  FORCE_INLINE linear_axis_bits_t axes_should_home(linear_axis_bits_t=linear_bits) { return false; }
-  FORCE_INLINE bool homing_needed_error(linear_axis_bits_t=linear_bits) { return false; }
-  FORCE_INLINE void set_axis_unhomed(const AxisEnum axis)   {}
-  FORCE_INLINE void set_axis_untrusted(const AxisEnum axis) {}
-  FORCE_INLINE void set_all_unhomed()                       {}
-  FORCE_INLINE void set_axis_homed(const AxisEnum axis)     {}
-  FORCE_INLINE void set_axis_trusted(const AxisEnum axis)   {}
-  FORCE_INLINE void set_all_homed()                         {}
+  inline void homeaxis(const AxisEnum axis)           {}
+  inline void set_axis_never_homed(const AxisEnum)    {}
+  inline linear_axis_bits_t axes_should_home(linear_axis_bits_t=linear_bits) { return false; }
+  inline bool homing_needed_error(linear_axis_bits_t=linear_bits) { return false; }
+  inline void set_axis_unhomed(const AxisEnum axis)   {}
+  inline void set_axis_untrusted(const AxisEnum axis) {}
+  inline void set_all_unhomed()                       {}
+  inline void set_axis_homed(const AxisEnum axis)     {}
+  inline void set_axis_trusted(const AxisEnum axis)   {}
+  inline void set_all_homed()                         {}
 #endif
 
-FORCE_INLINE bool axis_was_homed(const AxisEnum axis)       { return TEST(axis_homed, axis); }
-FORCE_INLINE bool axis_is_trusted(const AxisEnum axis)      { return TEST(axis_trusted, axis); }
-FORCE_INLINE bool axis_should_home(const AxisEnum axis)     { return (axes_should_home() & _BV(axis)) != 0; }
-FORCE_INLINE bool no_axes_homed()                           { return !axis_homed; }
-FORCE_INLINE bool all_axes_homed()                          { return linear_bits == (axis_homed & linear_bits); }
-FORCE_INLINE bool homing_needed()                           { return !all_axes_homed(); }
-FORCE_INLINE bool all_axes_trusted()                        { return linear_bits == (axis_trusted & linear_bits); }
+inline bool axis_was_homed(const AxisEnum axis)       { return TEST(axis_homed, axis); }
+inline bool axis_is_trusted(const AxisEnum axis)      { return TEST(axis_trusted, axis); }
+inline bool axis_should_home(const AxisEnum axis)     { return (axes_should_home() & _BV(axis)) != 0; }
+inline bool no_axes_homed()                           { return !axis_homed; }
+inline bool all_axes_homed()                          { return linear_bits == (axis_homed & linear_bits); }
+inline bool homing_needed()                           { return !all_axes_homed(); }
+inline bool all_axes_trusted()                        { return linear_bits == (axis_trusted & linear_bits); }
+
+void home_if_needed(const bool keeplev=false);
 
 #if ENABLED(NO_MOTION_BEFORE_HOMING)
   #define MOTION_CONDITIONS (IsRunning() && !homing_needed_error())
diff --git a/Marlin/src/module/stepper/indirection.h b/Marlin/src/module/stepper/indirection.h
index 4770fd4dc1..08d0be0b31 100644
--- a/Marlin/src/module/stepper/indirection.h
+++ b/Marlin/src/module/stepper/indirection.h
@@ -645,6 +645,11 @@ void reset_stepper_drivers();    // Called by settings.load / settings.reset
 
   #endif
 
+#elif ENABLED(E_DUAL_STEPPER_DRIVERS)
+  #define E_STEP_WRITE(E,V) do{ E0_STEP_WRITE(V); E1_STEP_WRITE(V); }while(0)
+  #define   NORM_E_DIR(E)   do{ E0_DIR_WRITE(!INVERT_E0_DIR); E1_DIR_WRITE(!INVERT_E0_DIR ^ ENABLED(INVERT_E1_VS_E0_DIR)); }while(0)
+  #define    REV_E_DIR(E)   do{ E0_DIR_WRITE( INVERT_E0_DIR); E1_DIR_WRITE( INVERT_E0_DIR ^ ENABLED(INVERT_E1_VS_E0_DIR)); }while(0)
+
 #elif E_STEPPERS
   #define E_STEP_WRITE(E,V) E0_STEP_WRITE(V)
   #define   NORM_E_DIR(E)   E0_DIR_WRITE(!INVERT_E0_DIR)
@@ -1013,6 +1018,7 @@ void reset_stepper_drivers();    // Called by settings.load / settings.reset
 //
 
 #if ENABLED(MIXING_EXTRUDER)
+
   /**
    * Mixing steppers keep all their enable (and direction) states synchronized
    */
@@ -1020,6 +1026,12 @@ void reset_stepper_drivers();    // Called by settings.load / settings.reset
   #define _CALL_DIS_E(N) DISABLE_STEPPER_E##N () ;
   #define  ENABLE_AXIS_E0() { RREPEAT(MIXING_STEPPERS, _CALL_ENA_E) }
   #define DISABLE_AXIS_E0() { RREPEAT(MIXING_STEPPERS, _CALL_DIS_E) }
+
+#elif ENABLED(E_DUAL_STEPPER_DRIVERS)
+
+  #define  ENABLE_AXIS_E0() do{  ENABLE_STEPPER_E0();  ENABLE_STEPPER_E1(); }while(0)
+  #define DISABLE_AXIS_E0() do{ DISABLE_STEPPER_E0(); DISABLE_STEPPER_E1(); }while(0)
+
 #endif
 
 #ifndef ENABLE_AXIS_E0
diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
index e7d4ece721..9274d0631e 100644
--- a/Marlin/src/module/temperature.cpp
+++ b/Marlin/src/module/temperature.cpp
@@ -333,6 +333,9 @@ const char str_t_thermal_runaway[] PROGMEM = STR_T_THERMAL_RUNAWAY,
     if (fan >= FAN_COUNT) return;
 
     fan_speed[fan] = speed;
+    #if REDUNDANT_PART_COOLING_FAN
+      if (fan == 0) fan_speed[REDUNDANT_PART_COOLING_FAN] = speed;
+    #endif
 
     TERN_(REPORT_FAN_CHANGE, report_fan_speed(fan));
   }
diff --git a/Marlin/src/pins/pins_postprocess.h b/Marlin/src/pins/pins_postprocess.h
index bd52e30454..ac4459bd02 100644
--- a/Marlin/src/pins/pins_postprocess.h
+++ b/Marlin/src/pins/pins_postprocess.h
@@ -543,9 +543,17 @@
 #define _EPIN(p,q) __EPIN(p,q)
 #define DIAG_REMAPPED(p,q) (PIN_EXISTS(q) && _EPIN(p##_E_INDEX, DIAG) == q##_PIN)
 
-// The X2 axis, if any, should be the next open extruder port
-#define X2_E_INDEX E_STEPPERS
+// The E0/E1 steppers are always used for Dual E
+#if ENABLED(E_DUAL_STEPPER_DRIVERS)
+  #ifndef E1_STEP_PIN
+    #error "No E1 stepper available for E_DUAL_STEPPER_DRIVERS!"
+  #endif
+  #define X2_E_INDEX INCREMENT(E_STEPPERS)
+#else
+  #define X2_E_INDEX E_STEPPERS
+#endif
 
+// The X2 axis, if any, should be the next open extruder port
 #if EITHER(DUAL_X_CARRIAGE, X_DUAL_STEPPER_DRIVERS)
   #ifndef X2_STEP_PIN
     #define X2_STEP_PIN   _EPIN(X2_E_INDEX, STEP)
diff --git a/buildroot/tests/DUE b/buildroot/tests/DUE
index 9931776e00..9eb2157428 100755
--- a/buildroot/tests/DUE
+++ b/buildroot/tests/DUE
@@ -24,7 +24,7 @@ opt_enable S_CURVE_ACCELERATION EEPROM_SETTINGS GCODE_MACROS \
            SKEW_CORRECTION SKEW_CORRECTION_FOR_Z SKEW_CORRECTION_GCODE CALIBRATION_GCODE \
            BACKLASH_COMPENSATION BACKLASH_GCODE BAUD_RATE_GCODE BEZIER_CURVE_SUPPORT \
            FWRETRACT ARC_SUPPORT ARC_P_CIRCLES CNC_WORKSPACE_PLANES CNC_COORDINATE_SYSTEMS \
-           PSU_CONTROL AUTO_POWER_CONTROL \
+           PSU_CONTROL AUTO_POWER_CONTROL E_DUAL_STEPPER_DRIVERS \
            PIDTEMPBED SLOW_PWM_HEATERS THERMAL_PROTECTION_CHAMBER \
            PINS_DEBUGGING MAX7219_DEBUG M114_DETAIL \
            EXTENSIBLE_UI
@@ -38,10 +38,9 @@ restore_configs
 opt_set MOTHERBOARD BOARD_RADDS NUM_Z_STEPPER_DRIVERS 3
 opt_enable USE_XMAX_PLUG USE_YMAX_PLUG ENDSTOPPULLUPS BLTOUCH AUTO_BED_LEVELING_BILINEAR \
            Z_STEPPER_AUTO_ALIGN Z_STEPPER_ALIGN_KNOWN_STEPPER_POSITIONS Z_SAFE_HOMING
-           #TOUCH_UI_FTDI_EVE LCD_ALEPHOBJECTS_CLCD_UI OTHER_PIN_LAYOUT
 pins_set ramps/RAMPS X_MAX_PIN -1
 pins_set ramps/RAMPS Y_MAX_PIN -1
-exec_test $1 $2 "RADDS with ABL (Bilinear), Triple Z Axis, Z_STEPPER_AUTO_ALIGN" "$3"
+exec_test $1 $2 "RADDS with ABL (Bilinear), Triple Z Axis, Z_STEPPER_AUTO_ALIGN, E_DUAL_STEPPER_DRIVERS" "$3"
 
 #
 # Test SWITCHING_EXTRUDER
diff --git a/buildroot/tests/LPC1768 b/buildroot/tests/LPC1768
index 95a055d695..b4e489d310 100755
--- a/buildroot/tests/LPC1768
+++ b/buildroot/tests/LPC1768
@@ -16,7 +16,7 @@ set -e
 restore_configs
 opt_set MOTHERBOARD BOARD_RAMPS_14_RE_ARM_EFB  SERIAL_PORT_3 3 \
         NEOPIXEL_TYPE NEO_GRB RGB_LED_R_PIN P2_12 RGB_LED_G_PIN P1_23 RGB_LED_B_PIN P1_22 RGB_LED_W_PIN P1_24
-opt_enable FYSETC_MINI_12864_2_1 SDSUPPORT SDCARD_READONLY SERIAL_PORT_2 RGBW_LED \
+opt_enable FYSETC_MINI_12864_2_1 SDSUPPORT SDCARD_READONLY SERIAL_PORT_2 RGBW_LED E_DUAL_STEPPER_DRIVERS \
            NEOPIXEL_LED NEOPIXEL_IS_SEQUENTIAL NEOPIXEL_STARTUP_TEST NEOPIXEL_BKGD_INDEX_FIRST NEOPIXEL_BKGD_INDEX_LAST NEOPIXEL_BKGD_COLOR NEOPIXEL_BKGD_ALWAYS_ON
 exec_test $1 $2 "ReARM EFB VIKI2, SDSUPPORT, 2 Serial ports (USB CDC + UART0), NeoPixel" "$3"
 
diff --git a/buildroot/tests/mega2560 b/buildroot/tests/mega2560
index 3ddb68fe88..0932388969 100755
--- a/buildroot/tests/mega2560
+++ b/buildroot/tests/mega2560
@@ -68,7 +68,8 @@ exec_test $1 $2 "Multiple runout sensors (x5) | Distinct runout states" "$3"
 #
 restore_configs
 opt_set MOTHERBOARD BOARD_AZTEEG_X3_PRO MIXING_STEPPERS 5 LCD_LANGUAGE ru \
-        NUM_RUNOUT_SENSORS E_STEPPERS FIL_RUNOUT2_PIN 16 FIL_RUNOUT3_PIN 17 FIL_RUNOUT4_PIN 4 FIL_RUNOUT5_PIN 5
+        NUM_RUNOUT_SENSORS E_STEPPERS REDUNDANT_PART_COOLING_FAN 1 \
+        FIL_RUNOUT2_PIN 16 FIL_RUNOUT3_PIN 17 FIL_RUNOUT4_PIN 4 FIL_RUNOUT5_PIN 5
 opt_enable MIXING_EXTRUDER GRADIENT_MIX GRADIENT_VTOOL CR10_STOCKDISPLAY \
            USE_CONTROLLER_FAN CONTROLLER_FAN_EDITABLE CONTROLLER_FAN_IGNORE_Z \
            FILAMENT_RUNOUT_SENSOR ADVANCED_PAUSE_FEATURE NOZZLE_PARK_FEATURE