Seperate them with a sap on ret pally possibly 2 if he trinkets, kill DK. With poisons and ruptures, disarm, bop wont save the dk. If it does, get away and wait for it to end, then repeat on dk.
You could each pretty much 1v1 them, just seperate them so you don't get caught in bladestorm or anything like that.
I haven't tried roguex2 yet, I usually run Rogue/DK or Rogue/Ret (wtb a decent mage to run with) and that always works for us.