Why do I have two profiles in Windows?

I hadn’t noticed this until today, but someone asked me why some computers had a profile for user01 and a profile for user01.domain. This got me to scratching my head because it seemed to be a good question for me and I usually dig until I find the answer out. This one wasn’t too hard to come up with, but it’s something that I hadn’t heard verbatim before. If there is already a profile folder with the same name as the user that you are logging on with, it will create the folder as user01.ComputerName or user01.DomainName. I’m still looking for how it decides that or what order it comes in, but that’s enough info to at least know what is happening.

Here’s a quote from wikipedia on user profile creation (windows xp but still seems applicable:
“At first logon, a folder will typically be created under “Documents and Settings” (standard folder on English version of Windows 2000, XP and Windows Server 2003) matching the logon name of the user. Should a folder of that name already exist, the profile-creation process will create a new one, typically named username.computername, on workgroup computers, or username.domainname on Active Directory member computers.”

Other Resources:
Fix a corrupt user profile in Windows 7

Update: Just found out a little more info about the possible order. If anyone has different experiences please post it in the comments.
Dave Patrick suggests the following order:
“On a newly-joined-to-the-domain PC if you logon to the pc first, then to the
domain you would end up with two profiles.
%username%
and
%username%.%userdomain%
Else if you logon to the domain first, then to the pc you would end up with
%username%
and
%username%.%computername%”

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