Don't understand what I may have done to end up with duplicated files in my library. Please advise.

I guess you're using LW 5?

If you've copied songs from your saved folder to another folder & that other folder's part of your library in LW 5 then you could see duplicates.

If you've added songs to a media player which stores files in a specific folder & that folder's part of your library in LW 5 then you could see duplicates

Just for eg - say you've added songs to iTunes' library. iTunes saves files to a folder within My Music. So if you've added My Music to your library you can end up with 2 copies of files... one copy from within LW's saved folder & one copy from within My Music.

If you go to My Library, right click on a file & choose 'Locate on Disk', the folder where the file is saved will open

You can remove the duplicate files from My Library & still have them saved to folders on your HDD. Or you can remove folders which contain copies of the files from your library. See the thread below for more info.
http://www.gnutellaforums.com/gettin...s-windows.html