Been thinking about this a fair amount lately. There is an optimum pinhole size per focal length (film to pinole distance). That said, any size pinhole will give you an image given enough exposure time. But... and this is a consideration with multiple pinhole systems, the length from pinhole to film is greater as you get away from the perpendicular of the pinhole to the film plane. If you look at good pinhole calculators, they will give coverage information. Now coverage info is just the size of image circle that you can expect a reasonably well exposed image at the edge of the circle without overexposing the center.
So what does that mean? If you know the image circle for a particular aperture pinhole and space several pinholes that far apart on the lens (?) board of your pinhole camera, you should have one image run into the other, with no sections of over (or under) exposed image between them. A photomontage blend. Calculate your exposures as if you had just one pinhole and expose either simultaneous or serially.
tim in san jose