Re: Dual accounts?
Dual accounts is understating it.
My wife's less intelligent friends are all constantly on FB playing games. They have special profiles just for the gaming so they don't constantly piss off regular users with all the game related requests which you need to send and acknowledge etc to get extra lives, or jewels or coins or whichever vacuous bullshit it is. I think that's very common. They're just engaged in a massive circle-jerk of sending each other requests that mutually benefits both parties in the game.
People have them for pets, business profiles for their "sticking glitter on glasses business" or their "I can bake cupcakes" business.
People have separate profiles for going in groups their partners wouldn't approve of, sleeping around, trolling or one of another hundred reasons. Then there's the kids. Hordes and hordes of kids both under, just on and just over the supposed minimum age. All of zero value to facebooks paying clients, the advertisers and the data-buyers.
*Then* on top of all that you have the bots, fake profiles, like farms etc etc etc. It's probably quite a high percentage of *items* on facebook that have zero value for advertisers.