Why am i having a gruesome death dream and why am i having it twice?

My dream was kinda blurry at the beginning. It was myself, but i could see myself and i aslo never got to see my face. And there were other people that i didn't know that were surrounding me, but there were only around 5 or 6 people. There is a killer on the loose and he is killing people for no reason in the world is what it seems like. I don't really know how he is killing them, but i see them after they are killed. Their faces are all chopped up, well actually their whole heads. In the end of my dream, for some reason the killer and i are by ourselves on an airplane, but it's hovering about a foot over gound and it's staying in that one spot and the roof is gone. Although it looks nothing like an airplane, i know that's what it was. The killer is holding a weedeater and he uses it to kill me. He turns it on and i watch my head being sliced and chopped. I then fall off the plane on to the ground. He throws his weapon onto the ground saying "Hahahaha, i have now had the most kills in the whole entire universe!" And then i appear again(also looking at myself)but my head or face is not mangled anymore, it's looks like he had never killed me. And i am behind him, walking towards him while he is laughing and chanting this. I say something, but i don't really remember what i said because it really didn't make any sense. But i push him off and he lands in a fire around a wooden fence pole(it looks like we are in some kind of field in the middle of no where)and all of a sudden it's starts to storm and lightning strikes him and that's the end of my dream, but lastnight was the SECOND time i have had this same dream.