Apple Infrared Face Authentication
The chance of finding people with simliar faces is 1 in 1,000,000 according to Apple WWDC Iphone X event.
So within a country of 100 million people like Vietnam, you could find 10 - 100 person with simliar faces. If these two twins have a large differences in social economic standing then here it is an arbitrage opportunity.
Government orgranizations like Public Security or big corporations like Facebook, Apple and Google have a massive database of user profile pictures and should be able to do query and look for similar faces within their citizens or users database.