I think I might know what happens here. If you cancel a rip because it is stuck, and then insert the next CD for ripping, the metadata for the first can carry over to the second. I definitely have a ripped CD by Free (Heartbreaker) where the filename is 'Blackie and the Rodeo Kings'. Of course, I would never know because the file plays correctly and the data in the library is all correct. I don't really look at the filename because I just look at 'Artist,' Name', 'Album' in the library columns. When I copy over some files, though, I could end up with two copies of the same album/tracks. They play right, but the filenames are different. Does that make sense?
Actually, I have ended up with 81 tracks all listed in the filename as being by The Black Keys, but none of them are by that artist.