I've never understood the two holes thing. Monos often leave such small holes that they leak much less blood than just the entrance of a cup and core.
Two holes generally means more blood on the ground, and more wiped off on vegetation as the critter goes through cover. Where I hunt, a lot of the cover is head-high weeds, with hummocks of grass and other stuff below, some of it red in color. Blood that drips out may fall into places you can’t see, so blood higher up is helpful. Also, an exit will likely spray some blood and hair, providing proof of a hit and maybe evidence of what sort. They don’t always bleed right away, even when hit with a powerful rifle, just as they don’t always drop, even when hit very hard in the right place. Tracking in the woods on leaves is much easier than in tall brushy weeds, where tracks are very hard to see.
