If you're Stun Locking one, and putting mass slows on the other, they will come in at the same time. My Group Slows + Stun Locks one, and only throws 1 stun onto the other. This would make it so the single stun comes after the 2nd ability of Brawler (In case it's a tank buster or AOE Stack) and the 2nd one will come in 5 seconds later.