Hey guys, I have had this issue as well, even reinstalled Windows twice with no luck. Uncheckboxing users must enter a user name and password to use this computer" in netplwiz does nothing either.
What you need to do is download this program:
Its called Autologon and it worked wonders for me!!! Upon booting up Windows, it automatically logs in now and bypasses the duplicate user account completely.
Ensure in netplwiz (start menu, run, type in netplwiz) you un-checkbox or turn off "users must enter a user name and password to use this computer"
I also have disabled the auto sign-in option. To do this,
1. Click on Start and Search and select settings
2. Select "Accounts"
3. Select "Sign in Options"
4. Scroll down to where it says "Use my sign in info to automatically finish setting up my device and reopen my apps after an update or restart" under Privacy and select OFF.
All this was done on my machine with the Fall Creators Update and works!!
Hope it works for you as well. I spent hours online checking useless advice on the forums -- none of which work. Give this one a try.