Movie Doppelgangers

[yanksno1]

I've been thinking about this recently. When I'm talking about Movie Doppelgangers, I'm thinking of movies that came out close to each other that have very similar story lines. One of those examples is Armageddon and Deep Impact. The other was White House Down and Olympus Has Fallen. I swear in both cases someone must have pitched a movie to a studio, they liked the idea but decided to pass and still take aspects of it and make a "fun" version of it. Think this is what happened in both of those cases? I think we know which movie ripped which haha (unless I'm totally wrong there). Haven't seen either of these new movies yet, but are Lamb and Antlers another case here? What are other movies I'm not thinking of that's happened to?