I'm using DNN5 for a customer's website and I've got AD authentication working to create accounts.  But I just noticed that when they get a browser prompt for the username and password, if they enter their username in as <domain>\<username> their account gets created with a username of <domain>\<username>,  but if they enter it in without the domain part, i.e <username> their ad account get created with just their usersname.

This is ok (I guess), but what I've found astounding is that when you enter the username once with the domain and once without it creates two accounts.

Both seperate accounts.  In the AD authentication config, I've put in the default domain, but I didn't think it was going to to this.

Is there a way to stop this, i.e recognise the same account regardless of whether the domain is entered or not?