Was I the only one????

Rating: 7/10 (27 August 2007)

I found this movie a little troubling because by the end, they still couldn't figure this thing out, when the answer was right there all along. I couldn't be the only one that saw this, but the movie acts as though it never happened. Let me explain...
When Robert Graysmith goes to meet with Bob Vaughn, he discovers that Vaughn was in fact the one who wrote the movie poster whose printing matched that of the letters send by the Zodiac to the newspaper. Vaughn then goes on to say that the Zodiac symbol could be the mark that is on the front of movie reels. He then leads him down to the basement where there are files and files of films and lots of things in storage.
While Graysmith and Vaughn are in the basement, Graysmith hears someone upstairs, but Vaughn insist there is no one there. Later in the movie, everything again appears to revert back to Arthur Leigh Allen as the prime suspect as he was identified by a surviving victim as the shooter in the first murder.
Does everyone see it now? There were actually two Zodiac Killers. Vaughn and Allen were working together. That is why Allen's writing samples didn't match the writing samples on the letters, because they were actually written by Vaughn. The two could have worked together to commit the murders or at the very least, Allen committed the murders while Vaughn wrote the letters.
It was so obvious to me, but I wonder why the film just kind of blew off the entire Vaughn/Graysmith scene as though it never happened. Was Graysmith just too blind to see the obvious or did the notion of two serial killers just seem to outlandish to consider? We now know such a thing is rare, but it does happen as was the case with serial killers Henry Lee Lucas and Otis Toole. These two maniacs were homosexual lovers and confessed to the murders of over a hundred people between them, although many were unsubstantiated. Never the less, they were convicted of many murders and remain two of the most notorious serial killers in American history.
Could Graysmith and Allen have had such a partnership? Why wasn't this idea even discussed in the movie? It was like Vaughn was considered as a suspect even though his handwriting was the closest match to the Zodiac letters. Could anyone help me out here?