Merge pull request #6817 from cbusillo/patch-1

missing enable for M605 for duplication mode

Marlin/Marlin_main.cpp

           break;
       #endif // FILAMENT_CHANGE_FEATURE
 
-      #if ENABLED(DUAL_X_CARRIAGE)
+      #if ENABLED(DUAL_X_CARRIAGE) || ENABLED(DUAL_NOZZLE_DUPLICATION_MODE)
         case 605: // M605: Set Dual X Carriage movement mode
           gcode_M605();
           break;