Then I wouldn't count 'em as a unit unless they were both unfriendly.
What? I'm the DM. I don't have to run things exactly the same way in every situation.
That sounds like a really good way to make a game frustrating and unfun for the players. I'd rather just have a reasonably consistent rule that makes sense, and I don't think being dragged around provokes more attacks than just lying there unconscious.