Extra logging of Dual X modes

Marlin/Marlin_main.cpp

                 current_position[X_AXIS] = destination[X_AXIS] + duplicate_extruder_x_offset;
               inactive_extruder_x_pos = RAW_X_POSITION(destination[X_AXIS]);
               extruder_duplication_enabled = false;
+              #if ENABLED(DEBUG_LEVELING_FEATURE)
+                if (DEBUGGING(LEVELING)) {
+                  SERIAL_ECHOLNPAIR("Set inactive_extruder_x_pos=", inactive_extruder_x_pos);
+                  SERIAL_ECHOLNPGM("Clear extruder_duplication_enabled");
+                }
+              #endif
               break;
           }
 
             );
           delayed_move_time = 0;
           active_extruder_parked = false;
+          #if ENABLED(DEBUG_LEVELING_FEATURE)
+            if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("Clear active_extruder_parked");
+          #endif
           break;
         case DXC_DUPLICATION_MODE:
           if (active_extruder == 0) {
+            #if ENABLED(DEBUG_LEVELING_FEATURE)
+              if (DEBUGGING(LEVELING)) {
+                SERIAL_ECHOPAIR("Set planner X", LOGICAL_X_POSITION(inactive_extruder_x_pos));
+                SERIAL_ECHOLNPAIR(" ... Line to X", current_position[X_AXIS] + duplicate_extruder_x_offset);
+              }
+            #endif
             // move duplicate extruder into correct duplication position.
             planner.set_position_mm(
               LOGICAL_X_POSITION(inactive_extruder_x_pos),
             stepper.synchronize();
             extruder_duplication_enabled = true;
             active_extruder_parked = false;
+            #if ENABLED(DEBUG_LEVELING_FEATURE)
+              if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("Set extruder_duplication_enabled\nClear active_extruder_parked");
+            #endif
+          }
+          else {
+            #if ENABLED(DEBUG_LEVELING_FEATURE)
+              if (DEBUGGING(LEVELING)) SERIAL_ECHOLNPGM("Active extruder not 0");
+            #endif
           }
           break;
       }