User blog comment:Mich, Michele & Kuhla/Future Units Preview/@comment-115.178.255.180-20150929055839/@comment-26464145-20150929122000

Yes it does, you can stack the different ATK buff, as long as it's not simple atk buffs (I mean, you can stack a simple ATK buff with a conversion (Libera, Owen) and with an element ATK buff (Signas)).