I wonder what exactly makes the rogue, well, a rogue. Aren't "Bad Bloods" that because they kill innocent and completely helpless prey? Hopper and his men were military, exactly the kind of prey that "Good Bloods" like to hunt. So what did the rogue do that was so evil? Did it steal it's arsenal, or a ship? Or another Predator's trophies?
Hey, maybe that's why Dutch mistook the good Predator for the rogue, the good one had just gotten it's stolen helmet and trophies back! You see, when Dutch roared, the good one, who was really far away from it's ship, got really scared! That's why it fought Dutch! When it took off it's helmet and gear, it had gone through so much that it just wanted to beat Dutch to death! It self-destructed as a F you to him for his unprovoked assault!
But wait, why did it mimic Billy's laugh if it never killed him? Because the rogue mimicked it during it's last fight against the good one, who recorded it! Also, notice the Jungle Hunter never wore human skulls? Just those of small alien critters? That means it didn't hunt humans! Ever! Making the fate of Saint-Predator all the more tragic!
But seriously, this story might make more sense if the rogue killed the good one, and if their encounter happened completely off-screen in the first movie. Though if they wanted an hostile encounter between two Predators, they should have just written an original story about it.