[Mailman-Developers] When a user is deleted, is the uid record intentionally not deleted?

I notice that when a user is deleted, the uid record remains.

Is this because there is a bug in which the uid should be deleted but is not?

or is this intentional behaviour to prevent the uid from being recreated as a duplicate?

My testing code does large numbers of creations and deletions of users so the deleted uid records are building up.