Very strange...
On my iPod with both Dido and Bjork present, if I select Dido's "Hunter" the song that plays is Bjork's "Hunter". I also have Dido's "Hunter" in a playlist, and again, the Bjork song plays.
However, if I plug my iPod to my computer and then select the Dido "Hunter" song on my iPod from the playlist or album in iTunes, it plays correctly.
However, I also have Dido's "Hunter" on there from a 2-disc album which plays normally. Also, if I select Bjork's "Hunter", the right Bjork song plays.
This is with my iPod 3G 15 GB (formatted to FAT32).