I'm not an engineer, but if it was 0.2-0.3mm off from a measurement stated in some sort of documentation, I would say maybe that was a design defect. When it is 2-3mm off from a product made by a different company, I would call that a manufacturing difference.

It would be cool to run two different chainrings bolted to each other, one for each cog, but that really depends on your chainring setup I guess. That way you could run a slightly larger chainring with the smaller cog so your wheel is still in the generally same spot in the dropouts when you flip your wheel around (to pull this off your chainring/cog combos must add up to the same number of teeth, I believe).