You aren't supposed to make a ddup folder, instead place the file "ddup_x.j" inside this folder: Warcraft III\jassnewgenpack5d\jass
If you still get the error, then you might need a special version of NewGen that DD released a long time ago. (He added some of his own functions, and you need the UI data for the map to load/save) I think the link was taken down though, so I recommend you get in contact with him if it doesn't work.
EDIT: Also, you can open ddup_x.j with notepad or any other text editing tool, copy the text, click on your map's header (open the trigger editor, and click your map's name listed above all the triggers), and then paste it all over there. Then remove the line //! import ddup_x.j or whatever it is.