🙂 excellent news.
My bet is that this happened b/c Apple told me to download the copypod software and copy everything from my ipod back onto my computer as a back-up for iTunes while they were trying to help my problem. My guess is that when iTunes launced, it read everything already in iTunes plus everything i copied over.
that sounds plausible.
if that is what happened, all the "new" songs should have the same "date added" information. so let's first bring up your "date added" column in your main library screen ("View > View Options", check "Date Added", click OK), and then click on the "Date Added" column header to sort the library on that column. that should gather together all of the "new" songs into a contiguous lump.
check to make sure that the the "new" song references are going to different music files than the "old" song references. probably the easiest way to confirm that is to take a sample of the "new" tracks, right-click the track name, select "Show in Windows Explorer". if they have are references to a completely different file, they should be showing up in different files locations from the "old" references when you do a Show in Windows Explorer on the old references.
if you've got doubled song files, select the new ones in the library screen and delete. (you can choose to get rid of the song files.)
if you've just got doubled references, delete from the main library window but choose
not to delete the song files. (you might want to doublecheck with a sample of the references, just to make sure this isn't messing with the "old" references to the files.
keep us posted on your progress.