Resolution

The user's Account Name may be the same as another user's Full Name. Remove the unwanted user with the duplicate name that you don't want to keep:

1. Determine which user you would like to keep by logging in as each of the users, checking the documents found in the user's home folder, and checking to see which user-specific information is shown in various applications (Safari, Mail, Address Book, iTunes, and so forth).
2. Log in as the user that you would like to remove, and choose Home from Finder's View menu. Make note of the name that appears at the top of the window that opens; this is unwanted user's "Account Name", which you will need in a later step.
   
   Note: If you used an advanced method to change the user's account name or home folder name in the past, you can skip this step and use the user's actual Account Name when needed in a later step.