Removing duplicate songs in an Apple Music playlist
The best and most comprehensive automation source for iTunes is Doug’s scripts. 


https://dougscripts.com/itunes/index.php


I would guess this is a pre-made script for this as is, and if not, you would probably have to use the duplicate finder you want and filter the input to only be playlists. You would need to sign in to your Apple Music on a Mac long enough to run that script of course. I’m guessing someone could make a Workflow automation that only runs on iOS but I havent come across some example of that yet. Maybe this jogs someone’s memory about a ready-to-run script in workflow app. 


Workflow by Apple https://itunes.apple.com/us/app/workflow/id915249334?mt=8