I’m also having a problem with duplicate artists, but only in Sorted by Most Played. In this mode, the top of the screen says 4910 of 1274, which is a good indicator of how many duplicates I am seeing. I haven’t figured out if there is anything unique about these artists, but one thing that is interesting is that there are no duplicates on the first page, but almost every other page has at least one duplicate artist (within the page).
With the other sort orders, I am not seeing any duplicates.