2 different engineer factions?

Well not sure if the alien engineers share the same sense for "logic" like humans do! That would even be interesting if they act and react based on a very "different" kind of "logic" as the logic and causality that we know and that are used to, that would be something "new" in my eyes. The engineer does never what you think he will do, he does thinks you would never expect and things that even make sense, in a very "abstract" way, maybe not understandable by human beings... Maybe you talk to him, but he scratches his leg the whole time and watches at the ceeling....he does not talk to you, but can do some "telepathic / telecinese sounds" that are reflected by the walls... or even some other strange unexpected wired stuff... haha.. i love this

I think the Engineer's culture was destroyed by bath salts...

Yes there is something as a second,either a second set of engineers or a higher force xeno which the engineers want to take on.