Hmmm. If the map service settings are all screwed up it might be easier to reinstall. You could also try deleting the duplicates in "manage repositories". If you don't have alot of downloaded maps to save you could also just delete the .db files.

Then once your finished with that, activate a map service in the menu (i.e. maps > Google Street). Next, go to "manage repositories" and set the "Cache DB" field to where you want to save the maps (mine is set to /media/mmc2/maps/GStreet.db). Now, you're ready to download maps.

To download maps from the active service for the area onscreen, go to "maps > manage maps > zoom". Now, choose zoom levels to download. Roughly, level 5 is neighborhood, 10 is city and 14 is state. Then, hit OK. A dialog will tell how big the download will be. I like to keep individual downloads to a couple MB, so if the size is too big I'll cancel and uncheck the lower zoom levels.

Repeat the process for any other services you want.