Torrents have two options:

Ideally you use Hardlinking - This creates a ‘copy’ of the file that’s just a link to the original data, instead of actually duplicating it. This only works when both ‘copies’ are kept on the same drive/filesystem; but gives you two versions so you can leave one available to seed and have one renamed and sorted away.

Failing that, it can fallback to plain duplicating the files. One copy kept to seed, and one copy sorted away.

Personally, I’ve switched to usenet for 99% of downloads, so seeding isn’t really a thing. It’s there as a fallback though.