To the main point I'm gonna say no. The tooltip explicitly says that the damage inflicted will be applied twice but the bonuses will not. For Armor Crush the bonus is the +30 seconds of Huton. If they should do anything it's change the little blurb when you hover over Duality in combat and change next weaponskill will strike "multiple times" to "twice". Because nitpick. Only ever seen it double the damage and not triple or quad it.