`duplicate_action: merge` creates new folder. Duplicates Plugin duplicates files (ironically)

While completing some of my already-downloaded incomplete albums, I've noticed that this "merge" option does NOT actually merge them path-wise.

This results in folder structures like this:
```
M:.
├───[2021] CHOCOLATE EN RAMA
├───[2021] Pirateship [4173]
├───[2021] Pirateship [5766]
└───[2024] Todo terreno
```

Between brackets it's, I'm guessing, the `catalognum` of beets, or the internal albumID of beets.

I've also set up my [Duplicates Plugin](https://beets.readthedocs.io/en/stable/plugins/duplicates.html)'s configuration to `merge: yes`, and it goes through the same process. So I guess Duplicates uses internally the same commands as beets itself.

Nor `beet update` or `beet move` help reordering the directories. And each time I use `beet dup -a`, it creates yet another copy of the same duplicate files and it does NOT add it to beet's database. Thanks to this, my library is a mess.