I noticed that many of the invalid labels that clutter up the database are constituted by two parts separated by a slash or brackets (more often than not, label and distributor, or even two valid and already existing labels).
Therefore, I suggest that we add a warning when users try to add new labels that have a slash or brackets in their name.

A first proposal for the confirmation box (feel free to adapt it):

The label you entered could be invalid or it could include both the label and the distributor. Please double-check the label on the release.

[checkbox] I confirm that this is a valid and single label.

We could also choose to expose the multiple labels feature in the warning, but that would create the risk of distributors being added as labels, which is not exactly the desired effect.

While this wouldn't allow us to catch all the fake labels invented by online stores, I think it would be a step in the right direction.