Posted 14 October 2011 - 08:40 AM
Itunes tend to duplicate titles if metatags of the original mp3 tracks contain "errors", which are really just accurate song information. Like, if some tracks of an album have extra Artists in addition to the original, then the album may duplicate. On pc, there's some good freeware utilities that help distill such "faulty" mp3 tags, e.g. Musicbrainz Picard, Magic MP3 Tagger or taghycardia. The latter is specifically designed to eliminate tag "errors" leading to duplicating albums in itunes and ipod.
You could try first to distill tags in the original mp3 files with any of those programs, and after correcting all the tag glitches reload the music folders into itunes to see if it helps.