Hello, and welcome to the forum!
This totally depends on a bunch of things, there’s no general answer. E.g.:
If you back up and let the hosts/users restore, and are fine with them being able to restore each others’ files, and especially if their backed up contents can benefit from deduplication between hosts, it makes a lot of sense to back them up into the same repository.
If you were to back up to REST-server with the append-only configuration, or were to not want hosts/users to be able to be able to restore each others’ data, or (perhaps less relevant) if your hosts wouldn’t benefit from deduplication between their data, it makes less sense to put them in the same repository.
Those were examples, there’s probably more factors involved too, but those are the general considerations.
I can’t speak for others. Personally, I would do separate backups instead of one backup which I then replicate/clone. The reasoning being that if there’s a corruption in that one backup, I don’t want it to exist in the only other copy of the backup I have. I’d rather have two individual backups, so one can become corrupted in case that happens, without affecting the other. Especially when you have two different types of storage, that’s good.
I know other people who’d just backup to one location and clone that repository using e.g. rclone or similar though. It’s kind of individual 