Seperate Beings???!

has anyone notice that in the new 30 second clip and in some of gifs, the difference in the being that grabs shaw and the one chasing someone to the door. Obviously the one grabbing shaw is burned to some degree. Therefore my theory is this being (burned) is either mutated fifield or at some point once this thing boards the prometheus someone gets a good shot at it with a flamethrower. another thing the being chasing someone isnt burned or at least not its back and from what we have seen from previous trailers fifield gets engulfed with flames .....the one chasing someone appears to be chasing vickers if we use the context of screen shots given.. Just a thought...cant wait