lot's of double dips i bet. i did and i've never played the game.Well it's the same with many other great sellers.
Still, even if we assumed all were double dippers (they're not, Sony said most were new buyers I believe early in the gen), that's still 8.5m sales for a new IP which is crazy
Hell I remember when the whole uncharted franchise reached 17m with UC1-3 and possibly Golden abyss lol