All sites I've ever belonged to have had fakes as well as doubles on them. This far I've never encountered a "safety system" that assures that people don't create fake accounts. Not even the sites who demands credit card information or your social security number can say that they have no fakes on it. Signing up to Facebook is as easy 1-2-3 and there are no demands on you to verify your identity, of course there will be fakes.
The company (Facebook) admitted that 5 percent to 6 percent of the accounts on its social network were fictitious or duplicative, amounting to about 42m of its 845m monthly active users.I don't use my real name online but I still have a Facebook account. I created it yesterday because I needed a Facebook account to get some free stuff from a company. (Not impersonating someone else, just making something up.) Reading today about how Facebook "require people to use their real names" made me smile. That said, I refuse to believe that the Facebook company really thought that they had no fake accounts. A Google search for "Facebook Fake Profiles" turns up over 3million hits and among them you'll find Facebook's own pages about how to report fakes.
Facebook has made a virtue of requiring people to use their real names and identities on the site, winning advertisers by providing access to real people.