You really believe that the ENTIRE ORIGINAL TRILOGY was supposed, back in 1974-1977, to be a single movie ?!?
I don’t know where you’ve read that (but it’s possible you’ve heard some bullshit like that, because GL never tells the truth), but there is absolutely no proof to suppot such a theory.
Take a look at these interviews :
http://uk.ign.com/articles/2002/11/11/an-interview-with-gary-kurtz