THIS IS THE ONLY ANSWER my shop found after working on this for days and trying many solutions. I hope it helps some of you. To review briefly - You go to login, there are two identical logins every time, only one shows in the user accounts/control panel. Every time you create another user account, no matter what name, it will duplicate it and show at the login. Very frustrating.
I can not take credit for the solution only the hunting = ) So thank you "Strider" On to what worked for us. >>>>>
Log into your computer using one of the duplicate accounts your wish to remove.
Open Windows Registry Editor (Start > Run > regedit.exe). (Run as admin)
In the left pane, navigate to the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication
Right-click and export the whole key and save it in a safe location. You'll need this file to restore the registry if something goes wrong in the below steps.
Now, navigate to the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\LogonUI
Make a note of the long string value associated with LastLoggedOnProvider. It should should like {01A30791-40AE-4653-AB2E-FD210019AE88}.
Now navigate to the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Authentication\CredentialProviders
Find the CredentialProvider that has the same string value noted in Step 6.
Right click on this item and create a new DWORD value named Disabled and give it a value of 1.
Close Regedit, logout, or restart and your problem should have disappeared.