There are many cases where a reorder required burning a new silk screen from existing artwork for a chip inlay. The realities of photo reproduction are that lines get broader as you keep recopying the same image multiple times. Try this with a copy machine that was designed in the 70's and you'll see it. My opinion is this doesn't generate a new chip variety, and that's the situation with the Riviera chips shown.

If it's obvious that the artist had to recreated the artwork (as in the Fremont 50c chip with the little guy with white or black F in his hat), I would consider it a different variety and would like to see it listed. I'd also rate chips with easily distinguishable mold differences as different varieties... like the long-cane and short-cane H&C molds.

Production variations, like differences in the registration of two colors in a multi-color inlay should not be grounds for listing a new variety either. Nor should differences in color, as ink colors can easily vary from lot to lot (or even day to day), and time can change inks depending on exposure to the elements.