I have Rhythmbox 2.97 on 32bit Ubuntu 12.10.
I have a large number of duplicate music entries that don't show up in my music folder.
I really would like to know if there's any plugin or any means to get rid of them.
It's happened to me a few times...
The easy way to solve this issue is:
The rhythmdb.xml file contains the music library info for Rhythmbox, by deleting it, you'll be forcing rhythmbox to re-check the library, thus getting rid of the repeated entries.
Some blogger wrote a GUI tool which automatically removes the duplicate entries from the rhythmbox database (without touching the actual files):