I think he'd need to use the force to separate them, sabers doesn't scale up as much as force powers.
I do not think Luke stomps people of this level working together. The whole numbers thing I often go on about it. I'd say he'd even be hard pressed, but that said, in the end my money is on Luke lasting enough for one of them to tire or for his force abilities to injure one. Then once he takes one out, it becomes a one-on-one duel.
Defeat is not out of the question for Luke, these are two powerful, skilled foes, but Skywalker takes a majority.