Actually I think that Chuck was just in denial, b/c after a while he said something about writing himself into the story, so he had written it but didn't want to admit it was true, or even possible. Its one thing to write "fiction" about demons, ghosts, and hunters, but it is another thing completly to have said hunters knocking at your door.
That's a good question! The only thing I can think of, judging by the way they are depicted on one of the book covers - bodybuilder physiques, one with super-long blonde hair, the other with shorter dark hair - is that Chuck was not given clear or accurate images of their faces in his visions. Perhaps he really was just recording "the word", and did not actually see images until his last vision when Zachariah showed up.
