Yes, we wrote about this at http://fbk.io/stopfakelikestoday http://fbk.io/stopfakelikestoday. In short Facebook could compare behaviour as you suggested (they'

Yes, we wrote about this at http://fbk.io/stopfakelikestoday http://fbk.io/stopfakelikestoday. In short Facebook could compare behaviour as you suggested (they've got a whole bunch of data scientists). An even more robust way would be making their phone number verification more thorough.