Systems Management

We have a Custom field that is using User.  Which displays the User Name.  There are many Users with similar names, and we are looking to make them unique by including their email address.

When Including User Information from an LDAP Authentication, This allows the Users to be searched based on their email address, but the custom field still only displays the user's name only.  How do we include the email address in the user name without affecting the user's login?

What we have so far:

What we would like to have: