Issue with duplicate requesters

I am having an issue where there are two requesters for a user. One is the AD pulled requester and the other is from their requester sending in emails. The emails for both requesters are the same.

Is there any fix for this, or reasoning behind it?

I verified that the Override setting is enabled in the Self service portal settings.

I know that the login name and email need to match for an overwrite, but when some users send an email, the emails come in with "Login name" as their full email. Is this an issue with configurations in outlook possibly?

The "bad" requester that gets made comes in with the "Name" field as their login name, the "Login Name" field as their username, and the "E-mail" field as their typical email.