Wildlife Spotting

I found these two wrestling on our door mat under the porch light. I am familiar with the brown june bug, but I don't know what this black one is. This is the first time I caught one beetle trying to eat another (I found the june bug's carcass hollowed out the next morning). At the point that I spotted them, the june bug wasn't putting up much of a fuss anymore & seemed to be incapacitated, though I didn't notice anything physical that would suggest it should be. -Perhaps the black beetle has a poisonous bite?