LOL! Twice the destruction!
I agree, it makes things complicated AND DC did have an Atlantis Amazon war for Flashpoint -- Not sure which came first, though I'm betting on Marvel. ;p However, it was was such a funny story, it is still my favorite.
Even if Marvel did have a clear timeline up to FF#1, it wouldn't matter, because writers keep retconning stuff, like Aaron's asinine One Million BC Avengers, which I believe predates the Celestials and makes the Norse gods older than the Cataclysm.