Fake.. obviously. Notice how he has to hold the top one when putting it in.. That's 'cause he doesn't want it to come off!
I have also heard of cases, and there is no reason it shouldn't happen sometimes. Usually when there are "defects" like that, the parents decide to have it removed. People can be born with extra arms and whatnot, but there is usually surgery to have them removed. It's not like they work.
People might be surprised to find all the things that people are born with that you don't see. Sometimes people are born with tails, a certain "genetic throwback" to our ancestry.