Two identical user names on logon screen - why?

Noticed that I am not the only one facing this issue after a fresh install.
One way or the other it will be solved, but I wonder why it is showing up in the first place?

Somewhere along the setup there is a screen that says:
"Who's going to use this PC? - What name do you want to use?"

What are users supposed to enter there? The first and last name, corresponding with the Microsoft account name?
Maybe, if the name inserted there is different from the Microsoft Account name (usually first name+last name), then two logins will show up??
Just a wild guess.

In my case two identical logins showed up (first name+last name) in the left hand bottom corner.

Yes, I always disable password requirement immediately (netplwiz).

Am not sure whether it has something to do with it... I tried following:
1. netplwiz, RE-enable password requirement-apply-reboot
then
2. RE-disable password requirement-apply-boot

Things went fine: no password requirement anymore.

Probably pure luck?

Hi Brink,
One of the first things I do is to run netplwiz, then untag the option, apply, reboot. There is only 1 account listed there.
Not sure how I should/could do it differently to be honest.
I do this because I hate to login each time at rebooting during the setup of applications, etc.
That aside, I am the only user.

As said, when setting up Windows, I get this 'Who is going to be using this PC' and I don't exactly know what to insert there.
First name, last name or just first name?
And what if the name there differs from the account (full) name?
No idea whether that is causing a 'conflict'.