After a manipulation or a move (like Windows Easy Transfer) of music maps (+listings) there are sometimes lots of doubles (tracks) genererated at reinstall of the player in WMP and this phenomenon occurs also in iTunes. You can of course remove them manually one by one but sometimes it's quite a job and a bit so called occupational therapy! It would be handsome to have a command available to remove them all together, in iTunes they are talking somewere of doubles I think or recall but I did not elaborate further on this item at that time.