Implement DUAL_NOZZLE_DUPLICATION_MODE

Marlin/Marlin.h

 
 void manage_inactivity(bool ignore_stepper_queue = false);
 
-#if ENABLED(DUAL_X_CARRIAGE)
+#if ENABLED(DUAL_X_CARRIAGE) || ENABLED(DUAL_NOZZLE_DUPLICATION_MODE)
   extern bool extruder_duplication_enabled;
 #endif
 

Marlin/Marlin_main.cpp

 XYZ_CONSTS_FROM_CONFIG(float, home_bump_mm,   HOME_BUMP_MM);
 XYZ_CONSTS_FROM_CONFIG(signed char, home_dir, HOME_DIR);
 
+#if ENABLED(DUAL_X_CARRIAGE) || ENABLED(DUAL_NOZZLE_DUPLICATION_MODE)
+  bool extruder_duplication_enabled = false; // Used in Dual X mode 2
+#endif
+
 #if ENABLED(DUAL_X_CARRIAGE)
 
   #define DXC_FULL_CONTROL_MODE 0
   static millis_t delayed_move_time = 0; // used in mode 1
   static float duplicate_extruder_x_offset = DEFAULT_DUPLICATION_X_OFFSET; // used in mode 2
   static float duplicate_extruder_temp_offset = 0; // used in mode 2
-  bool extruder_duplication_enabled = false; // used in mode 2
 
 #endif //DUAL_X_CARRIAGE
 
     current_position[X_AXIS] = current_position[Y_AXIS] = 0.0;
     sync_plan_position();
 
-    #if ENABLED(DUAL_X_CARRIAGE)
-      int x_axis_home_dir = x_home_dir(active_extruder);
-      extruder_duplication_enabled = false;
-    #else
-      int x_axis_home_dir = home_dir(X_AXIS);
-    #endif
+    int x_axis_home_dir =
+      #if ENABLED(DUAL_X_CARRIAGE)
+        x_home_dir(active_extruder)
+      #else
+        home_dir(X_AXIS)
+      #endif
+    ;
 
     float mlx = max_length(X_AXIS),
           mly = max_length(Y_AXIS),
     tool_change(0, 0, true);
   #endif
 
+  #if ENABLED(DUAL_X_CARRIAGE) || ENABLED(DUAL_NOZZLE_DUPLICATION_MODE)
+    extruder_duplication_enabled = false;
+  #endif
+
   /**
    * For mesh bed leveling deactivate the mesh calculations, will be turned
    * on again when homing all axis
     if (home_all_axis || homeX) {
       #if ENABLED(DUAL_X_CARRIAGE)
         int tmp_extruder = active_extruder;
-        extruder_duplication_enabled = false;
         active_extruder = !active_extruder;
         HOMEAXIS(X);
         inactive_extruder_x_pos = current_position[X_AXIS];
     delayed_move_time = 0;
   }
 
-#endif // DUAL_X_CARRIAGE
+#elif ENABLED(DUAL_NOZZLE_DUPLICATION_MODE)
+
+  inline void gcode_M605() {
+    stepper.synchronize();
+    extruder_duplication_enabled = code_seen('S') && code_value_int() == 2;
+    SERIAL_ECHO_START;
+    SERIAL_ECHOPAIR(MSG_DUPLICATION_MODE, extruder_duplication_enabled ? MSG_ON : MSG_OFF);
+    SERIAL_EOL;
+  }
+
+#endif // M605
 
 #if ENABLED(LIN_ADVANCE)
   /**

Marlin/language.h

 #define MSG_ENDSTOP_HIT                     "TRIGGERED"
 #define MSG_ENDSTOP_OPEN                    "open"
 #define MSG_HOTEND_OFFSET                   "Hotend offsets:"
+#define MSG_DUPLICATION_MODE                "Duplication mode: "
 
 #define MSG_SD_CANT_OPEN_SUBDIR             "Cannot open subdir "
 #define MSG_SD_INIT_FAIL                    "SD init fail"

Marlin/stepper_indirection.h

   #define NORM_E_DIR() { switch (current_block->active_extruder) { case 0: E0_DIR_WRITE(!INVERT_E0_DIR); break; case 1: E1_DIR_WRITE(!INVERT_E1_DIR); break; case 2: E2_DIR_WRITE(!INVERT_E2_DIR); } }
   #define REV_E_DIR() { switch (current_block->active_extruder) { case 0: E0_DIR_WRITE(INVERT_E0_DIR); break; case 1: E1_DIR_WRITE(INVERT_E1_DIR); break; case 2: E2_DIR_WRITE(INVERT_E2_DIR); } }
 #elif EXTRUDERS > 1
-  #if DISABLED(DUAL_X_CARRIAGE)
+  #if DISABLED(DUAL_X_CARRIAGE) && DISABLED(DUAL_NOZZLE_DUPLICATION_MODE)
     #define E_STEP_WRITE(v) { if (current_block->active_extruder == 0) { E0_STEP_WRITE(v); } else { E1_STEP_WRITE(v); } }
     #define NORM_E_DIR() { if (current_block->active_extruder == 0) { E0_DIR_WRITE(!INVERT_E0_DIR); } else { E1_DIR_WRITE(!INVERT_E1_DIR); } }
     #define REV_E_DIR() { if (current_block->active_extruder == 0) { E0_DIR_WRITE(INVERT_E0_DIR); } else { E1_DIR_WRITE(INVERT_E1_DIR); } }