Urgh, same here!
I feel it's a pretty normal flow to go through:
- Find something you like on Apple Music
- Add it to library, listen a bunch, put it in some playlists
- Decide to buy it to support the artist and have it long-term (and to listen on an iPod every now and then)
- Add to Apple Music on Mac
- Duplicates! 😭
I find Cloud Sync works ~60% of the time? I have dupes that show fine on my Mac but don't show on my iPhone (presumably because they didn't match? I dunno)
Some kind of "merge tracks" flow where you take the playlist membership and play count from Apple Music (and Spatial/Atmos audio if you want to listen to that sometimes) but make the purchased version the 'main' one would be great, but that doesn't seem to exist.
Similarly, there doesn't seem to be a way to force the matching to try again, or manually match two tracks. I get this is maybe a niche experience, but it does push people away from using Apple Music as having an unreliable library that just breaks every now and then might not be worth the 'Apple' experience, and you'd be better off manually managing it with something else, switching the iPod to Rockbox, etc.