Jeffrey, I did consider this kind of thing. I haven't tried it before so I wonder what the reproduction quality would be like to photograph prints, in terms of the resolution, contrast, dynamic range and so on. Might have to give it a go.
Alternatively I could probably make 4 near-identical 35mm negatives at the time the picture is taken, although I'd rather they were actually identical. There's a possibility of shooting the picture on transparency which can then be easily copied onto B&W negatives multiple times.
I'm certain it would be cheaper and easier to get the prints made at a lab or even (shock, horror) digitally - but I'm adamant I want to handle the creation of these pictures myself by hand.