Two (or more) playlists when removing duplicates

[ammoscoso]

I think it would be nice to have an option to input two (or maybe even more) playlists to the remove duplicates feature.

Sometimes the playlists are already at maximum size and can't be merged, making it not possible to treat them as a single one to use this feature.

Or the user might not want to merge the playlists but still don't want to have the same song on more than one of them.

[apastel]

It's probably not something I have the bandwidth for but I see you forked it so let me know how it goes, if it ends up working be sure to open a PR to merge it back here :)

[ammoscoso]

Managed to get it working on my system, tested against multiple combinations of playlists with thousands of duplicates.

Here is a quick breakdown of what I modified:

Multiple Arguments: Updated the remove-duplicates command in cli.py to accept multiple playlist names at once (nargs=-1).

Playlist Tracking: Modified duplicates.py to inject the _playlist_id and _playlist_title into each track's metadata. This way, the script knows exactly which playlist to delete the duplicate from. I also added the playlist name to the interactive prompt so users can easily see where each duplicate is located in the message.

Exponential Backoff (Anti-Crash): When I tested this with a massive combination of playlists (I had over 17,000 duplicates!), the script crashed with an HTTP 409: Conflict error because the YouTube Music API couldn't keep up. To fix this, I added a retry loop with exponential backoff (1s, 2s, 4s...). Now, if the API gets overwhelmed, the script just pauses briefly and retries instead of failing. If fixed all erros here just on the first step.

I just opened the PR for this! Full disclosure: I'm not a professional dev and this is actually my very first PR, so I hope I didn't mess anything up. :)

Thanks for the awesome tool!