LDAP with Username

Trying to get Filerun to work with username or email address with Active Directory for the company. I can get them to use either <username> or <email address> as a login with "(&(objectclass=user)(|(sAMAccountName={USERNAME})(mail={USERNAME})))" for the search template.

Problem is if they login with their username and then email address it will create 2 separate accounts. How do we allow them to login with either username or email address but both will connect as just username?