Hi Simon
The username is used as a key.
At the moment when you delete a user all permissions for that user should be tidied up. Removing deleted users from groups is an outstanding bug that will be fixed in the next release.
The recipient table is just a list of all recipients, an entry here does not matter. An entry in the node_perm_entry.recipient would be an issue, these should be deleted.
Can you tell me:
* which authentication service you are using;
* and how you are adding people and users.
I will then try and reproduce this.
Deleting a user means deleting the user and the person.
The user list is in fact generated from a list of all the people.
It sounds like the user has been deleted the first time and not the person or there were multiple people linked to the same user name, one was deleted, which deleted the user and you now have a dangling person.
The first is unlikely the second possible if you are bulk loading poeple.
Regards
Andy