To change the DupeNuker database that NewzScape uses, go to:
Setup Menu -> Settings -> DupeNuker
When you have the DupeNuker setting turned on for a newsgroup, NewzScape will use the database file specified here. You may want to change this setting if you need to store the database file at a different location. Also, if you are using the stand-alone DupeNuker software, you can use this setting to tell NewzScape to use the DupeNuker.sdb database file.