Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

If you only want to find duplicates give czkawka a try. It has a nice GUI too.

I don't know how good it is for music duplicates I only used it to find duplicate pictures and worked very well !

I just wrote a PowerShell script to do this for my pictures comparing file names and sizes. Should be able to find something similar with a search. Might not work for what you're looking for unless they were exact copies though.

https://beets.io/ could do all of that for you.

MusicBrainz Picard is a software for tagging and organising music. It can apply the tags directly to the file and then move them into a folders like Music\Album\01-Song.mp3

An easy way to spot duplicates at that point is search for any songs that have (1) or (2) and so on in the file name.

Then you can use basically any music player to sort by title to check for duplicates, too.

Not ideal, but what I do is to load all musics onto VLC, open the list view (Ctrl L on Linux), let the list fully load, sort by song name and check what appears repeated or that I don't want for other reasons. It also helps if the songs are metadata-rich, such as the ones bought from Bandcamp and ITunes (not Apple Music), so it's easier to differentiate them (given this community, I have no clue how/where from yours are). And lastly, there's a little plugin I found a while back that helps a bunch, vlc-delete, which adds the option to delete the currently playing file, and that, at least in the Linux version, benefits from motor memory since it can be executed with a quick succession of 2 Alt shortcuts.

When I did this recently I used Lexicon DJ management (as I'm a DJ and it has lots of other features I was using too).

There are a few options to choose from in terms of how it searches and how strict it is when trying to find duplicates. I'm not sure which features are available on the free version, I paid just for one month to sort out a lot of things within my DJ library but it may be worth looking in to to see if it can serve your needs :)

edit to add more info

Website says - "With Find Duplicates you can scan all your tracks in your library and automatically compare them based on the audio signature or tags. This way truly identical audio duplicates are found. This even works with different file types. If you have an MP3 and a WAV with the same audio, Lexicon will match them and lets you choose which one you want to keep."

So it doesnt just scan filenames it compares the audio files themselves to weed out duplicates.

Here is a YT video of the process from their site