Perhaps someone can help me out.
I just acquired a 70mm back for my 4x5 and have come across some attractive offers on slightly dated dupe films.

OK.. explain to someone who's a bit sleep deprived. What sort of results do you get from using a dupe film as your original?

Although this isn't the color forum I'll ask the same question for color film.. What's the difference?

I would assume a dupe film would be tuned for a flat response, low grain, etc.. but it seems to me a possible way of shooting a lot of film quite inexpensively.... unless I'm dramatically mistaken

Thanks in advance for any perspective, advice or experience.