Prometheus: Two Films Perhaps Made

It is a common trend when making a trilogy, to shoot all three films at the same time. This can be clearly seen with Peter Jackson in the Lord of the Rings and the upcoming Hobbit film. In the case of Prometheus, we got story that really moved fast and of course, left wide open with many questions that will be saved for the secondary film. Working in film for a couple of years, to ask this question, did Scott make two films, one would have to look at the time it took for this film to come out. How long was the production? Of course, could they be keeping this so tight under wraps that the no one but only a handful of the production crew know. Of course, what does 10-11-12 be? Possibly the DVD release or not. Of course there is the Magellan set piece we saw many months ago when things were being leaked out. So, I am guessing the sequel has already been touched upon, perhaps parts filmed already.... So let it begin... Remember, what does not kill you, simply makes you stranger.. Mr.J