When browsing through my music collection in the Xbox Music app today, I noticed that one of the albums is shown twice:
At first I thought it was the same split album issue as this question, but it's not - both entries actually contain the entire track listing of the album:
The first copy is an offline version of the album (which I downloaded from the Xbox Music catalogue a while back), while the second one is streaming-only (as can be seen from the download buttons and streaming icons for each track). So far this is the only album on my phone with this problem, all others from my Xbox Music collection are shown correctly.
I thought that there might actually be two versions of the album in the Xbox Music catalogue, and I've downloaded one to my phone and added the streaming version of the second on another device, but that doesn't seem to be the case.
What's the problem and how can I get rid of the extraneous streaming-only copy? Also, how can I prevent this from happening in the future? I'd like to avoid playing the wrong version by accident and needlessly using up mobile data when I have an offline copy of the album sitting on my phone.