I have a playlist called Discover weekly archive which uses IFTTT to automatically add songs from Discover weekly to the archive. When I opened Spotify today, I had about 15-20 copies of a playlist called Discover weekly archive. So it has copied itself. Also, there is only about 10 songs which I don't even recognize on the duplicated playlists. Why dis?
I think it was some problem with IFTTT itself because I had a similar issue yesterday - it created a new playlist every time instead of adding to existing one. Seems to be fixed now though. Do you still have this problem?