Fix up Dual X switch blocks

Marlin/Marlin_main.cpp

     stepper.synchronize();
     if (code_seen('S')) dual_x_carriage_mode = (DualXMode)code_value_byte();
     switch (dual_x_carriage_mode) {
+      case DXC_FULL_CONTROL_MODE:
+      case DXC_AUTO_PARK_MODE:
+        break;
       case DXC_DUPLICATION_MODE:
         if (code_seen('X')) duplicate_extruder_x_offset = max(code_value_axis_units(X_AXIS), X2_MIN_POS - x_home_pos(0));
         if (code_seen('R')) duplicate_extruder_temp_offset = code_value_temp_diff();
         SERIAL_CHAR(',');
         SERIAL_ECHOLN(hotend_offset[Y_AXIS][1]);
         break;
-      case DXC_FULL_CONTROL_MODE:
-      case DXC_AUTO_PARK_MODE:
-        break;
       default:
         dual_x_carriage_mode = DEFAULT_DUAL_X_CARRIAGE_MODE;
         break;
             if (DEBUGGING(LEVELING)) {
               SERIAL_ECHOPGM("Dual X Carriage Mode ");
               switch (dual_x_carriage_mode) {
-                case DXC_DUPLICATION_MODE: SERIAL_ECHOLNPGM("DXC_DUPLICATION_MODE"); break;
-                case DXC_AUTO_PARK_MODE: SERIAL_ECHOLNPGM("DXC_AUTO_PARK_MODE"); break;
                 case DXC_FULL_CONTROL_MODE: SERIAL_ECHOLNPGM("DXC_FULL_CONTROL_MODE"); break;
+                case DXC_AUTO_PARK_MODE: SERIAL_ECHOLNPGM("DXC_AUTO_PARK_MODE"); break;
+                case DXC_DUPLICATION_MODE: SERIAL_ECHOLNPGM("DXC_DUPLICATION_MODE"); break;
               }
             }
           #endif
    */
   inline bool prepare_move_to_destination_dualx() {
     if (active_extruder_parked) {
-      if (dual_x_carriage_mode == DXC_DUPLICATION_MODE && active_extruder == 0) {
-        // move duplicate extruder into correct duplication position.
-        planner.set_position_mm(
-          LOGICAL_X_POSITION(inactive_extruder_x_pos),
-          current_position[Y_AXIS],
-          current_position[Z_AXIS],
-          current_position[E_AXIS]
-        );
-        planner.buffer_line(current_position[X_AXIS] + duplicate_extruder_x_offset,
-                         current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], planner.max_feedrate_mm_s[X_AXIS], 1);
-        SYNC_PLAN_POSITION_KINEMATIC();
-        stepper.synchronize();
-        extruder_duplication_enabled = true;
-        active_extruder_parked = false;
-      }
-      else if (dual_x_carriage_mode == DXC_AUTO_PARK_MODE) { // handle unparking of head
-        if (current_position[E_AXIS] == destination[E_AXIS]) {
-          // This is a travel move (with no extrusion)
-          // Skip it, but keep track of the current position
-          // (so it can be used as the start of the next non-travel move)
-          if (delayed_move_time != 0xFFFFFFFFUL) {
-            set_current_to_destination();
-            NOLESS(raised_parked_position[Z_AXIS], destination[Z_AXIS]);
-            delayed_move_time = millis();
-            return false;
+      switch (dual_x_carriage_mode) {
+        case DXC_FULL_CONTROL_MODE:
+          break;
+        case DXC_DUPLICATION_MODE:
+          if (active_extruder == 0) {
+            // move duplicate extruder into correct duplication position.
+            planner.set_position_mm(
+              LOGICAL_X_POSITION(inactive_extruder_x_pos),
+              current_position[Y_AXIS],
+              current_position[Z_AXIS],
+              current_position[E_AXIS]
+            );
+            planner.buffer_line(current_position[X_AXIS] + duplicate_extruder_x_offset,
+                             current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], planner.max_feedrate_mm_s[X_AXIS], 1);
+            SYNC_PLAN_POSITION_KINEMATIC();
+            stepper.synchronize();
+            extruder_duplication_enabled = true;
+            active_extruder_parked = false;
           }
-        }
-        delayed_move_time = 0;
-        // unpark extruder: 1) raise, 2) move into starting XY position, 3) lower
-        planner.buffer_line(raised_parked_position[X_AXIS], raised_parked_position[Y_AXIS], raised_parked_position[Z_AXIS], current_position[E_AXIS], planner.max_feedrate_mm_s[Z_AXIS], active_extruder);
-        planner.buffer_line(current_position[X_AXIS], current_position[Y_AXIS], raised_parked_position[Z_AXIS], current_position[E_AXIS], PLANNER_XY_FEEDRATE(), active_extruder);
-        planner.buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], planner.max_feedrate_mm_s[Z_AXIS], active_extruder);
-        active_extruder_parked = false;
+          break;
+        case DXC_AUTO_PARK_MODE:
+          if (current_position[E_AXIS] == destination[E_AXIS]) {
+            // This is a travel move (with no extrusion)
+            // Skip it, but keep track of the current position
+            // (so it can be used as the start of the next non-travel move)
+            if (delayed_move_time != 0xFFFFFFFFUL) {
+              set_current_to_destination();
+              NOLESS(raised_parked_position[Z_AXIS], destination[Z_AXIS]);
+              delayed_move_time = millis();
+              return false;
+            }
+          }
+          delayed_move_time = 0;
+          // unpark extruder: 1) raise, 2) move into starting XY position, 3) lower
+          planner.buffer_line(raised_parked_position[X_AXIS], raised_parked_position[Y_AXIS], raised_parked_position[Z_AXIS], current_position[E_AXIS], planner.max_feedrate_mm_s[Z_AXIS], active_extruder);
+          planner.buffer_line(current_position[X_AXIS], current_position[Y_AXIS], raised_parked_position[Z_AXIS], current_position[E_AXIS], PLANNER_XY_FEEDRATE(), active_extruder);
+          planner.buffer_line(current_position[X_AXIS], current_position[Y_AXIS], current_position[Z_AXIS], current_position[E_AXIS], planner.max_feedrate_mm_s[Z_AXIS], active_extruder);
+          active_extruder_parked = false;
+          break;
       }
     }
     return true;