Googling will reveal issues with duplicated artists to be fairly common, but the solutions always center around fixing spelling errors, removing spurious spaces, or cleaning up other textual errors in the tags. Since I'm a MusicBrainz tag nazi, this isn't the problem for me. After a bit of flailing and comparing tracks from these problematic artists, I found the cause for all the problems in my collection boiled down to:
- Different id3v2 versions
- Different sort names
Fixing problem (1) was easy. I converted all tracks to id3 v2.4, which they probably should have been already. This was a simple matter of selecting all tracks, right clicking, and selecting the "convert tags..." option.
Problem (2) was about as simple, but much more tedious. I scanned through looking for dupes in the iTunes artist list, and unified all the tracks to the same sort name. Unfortunately, iTunes wouldn't allow me to change this option en masse, so I had to do one at a time.
After I finished, I noticed there were still a few repeated artists left in the iPod, but not repeated in iTunes. Loading the collection back up in iTunes, I realized these few remaining were due to yet another problem:
- Some tracks missing a sort name
Which is sort of a variant of problem (2), but only affected the iPod. This time I could either add a sort name to some of the tracks, or remove it from the others. I opted for an economy-of-motion approach. I decided separately for each artist, depending on which option would require the fewest changes. I don't like having sort names for only some artists, but considering that iTunes only let me do one at a time, I bit the bullet and saved myself some time.