Maybe it's not a bug but I do something wrong, but it sure looks like it.
- First I imported a bunch of movies from a directory (search HD for movies) - Then I run some scripts for imdb info and covers - Then I added more movies in the same directory - Then I scanned the same directory again, with the "only a movies not already in DB (if you scan HD...)" option checked.
XMM still imported also the movies I had already imported earlier on and created double entries.