I keep getting exact duplicate songs in playlists and libraries, how can you filter this out when upgrading these lists, or sync to the same device again? And how to do it without going through each and every P'list or Library ?

Question

I have Windows XP-Pro SP3, the latest upgrades of Three media players, iTunes being the default player. I keep getting duplicates in playlists, libraries etc., of the same version of song. Everytime i make a change or renew my media to device or SYNC it wants to add duplicates to the computer disk, lists etc. Can you filter out same copies without having to edit each and every song, which in my case is quite large. For instance if you want to convert all mpeg, or mp4-a files to AAC you will end up with duplicates of each file type. Or you sync to an ipod, the library adds to itself---- including copies of songs already in it, if in a different file version.

Answer 1

Your refer to:
" if you want to convert all mpeg, or mp4-a files to AAC "
This will always duplicate files within iTunes.  I need to ask why you're doing this conversion - all formats are compatible with iTunes, and conversion between mp3 and AAC will always involve some loss of quality.