How does facebook know I'm not really Dean Winchester?

[Kellin Quinn]

Basically I was bored and being a fan of supernatural i decided to make a facebook account for Dean from it (not a page, a personal account). I typed in the details and used the same email address as my actual facebook account and it said i already had an account, so i changed the email address to my other email and still it wouldn't let me create an account. It said: We require everyone to use their real name on Facebook. Learn more. I clicked Learn more and my name followed all of the guidelines so why didn't it work? It still didn't work when i changed Dean to Sam. Does facebook know that Dean Winchester is a character?
Thanks for the answers everyone, they all helped me out equally i can't pick a best one

[Jan]

maybe if you had an email address dean.winchester@mail.me it wouldn't give you that message?
Facebook has some real crappy scripts that do checks on names, but what is going on under the hood is something only the facebook developers know.

[Earth ◊³ Dee]

I'm gonna take a guess and say your real name isn't Banana either.

I don't know how FB does it, but I will guess that with popular actors/characters they probably get a lot of people trying what you are trying. Maybe they looked at your IP address and have a record of you connecting to your real account using it, so they weren't fooled.

This situation might suck if your name was really the same as a famous one. I suspect you'd have to send FB a picture of your driver's license proving you are who you say.

[Josh]

if someone famous has a page that is specifically named after them and it is set up to be a fan page facebook will not let you create a personal account using the same name.