I don't think this is going to work. the "Username" field in your configuration can only take a single parameter ... and we explicitly search for that parameter called "UserPrincipalName". Have you looked at the LDAP attributes for the user to see exactly how things are listed?
The second part to this is that each user is unique as per the login (aka Username value). vCloud Director doesn't support alternative login names for users (two logins for 1 account) as far as I know.