It depends on whether you think the addition of a second hand is more likely to be another made hand or another heart draw. If you are behind to one made hand...in fact dominated by a KJ, you are still a 55% favorite. If you add the Ah draw you drop to 21%.
I agree there may not be enough information on the hand to put either one solidly on the Ah draw, I think that may be more likely than adding a second made hand that feels strongly enough for the all ins.
If you weight the two at 50:50 you are down to a 2:1 dog, you dont lead the flop and things play pretty differently. Even if you give the Ah draw 25% weight you are down to 60:40 dog. Now you may lead at it or check...hard to say.
Even giving a range of just every suited ace, KQ and 77 for both players, we are 28%.
We could start applying realistic ranges for both players, but I have no doubt that it would show a call.
MP1 pushes any king, a set, JT or any heart draw, plus maybe a few others. He might even go crazy with QX.
MP2 pushes any king, a set and possibly AhXh, plus maybe a few others.
Remember that they might not have AhXh. It could be a lower draw and KJ.