@noris -
Did you ever solve this?
I ask because since I’ve switched to running ROCK, I have the same problem.
It seems to increase over time or over ROCK startups, maybe. I originally had two now I have three.
Nothing changes on my system. I just switch my core from WIN10 to ROCK (two different machines) and back, etc.
If I delete the duplicates and leave one, then they all disappear and Roon complains it can’t find any displays.
Doesn’t really affect anything, just a odd bug.