Whenever I shuffle play an artist, tracks are constantly duplicated. I'm not sure when this problem appeared, but it's been within the last month or two. I've read some other answers (eg this one) that seem to suggest it's a known issue (ie Spotify has broken and is adding popular songs to the full playlist). However, I haven't seen anything that talks about how pernicious this problem is. I was able to play an artist, shuffle the tracks, encounter a double, unshuffle, and repeat (scroll down to see this visually). If that's the intended behavior that makes absolutely no sense.
Steps to Reproduce
1. Select an artist
2. Shuffle play the artist
I threw together a quick video to illustrate the issue. Swapping from shuffle to plain and back consistently shows the same broken behavior.