I think he's saying that one carcase member is a different length than it's opposing part. This would cause corner-corner measurements to be dead on, but with a slight taper, that would be evenly distributed to both sides.
I suppose you could split the difference .. apply a very thin tapered shim to each opposing member of the carcase .. then cut the inset doors at a very slight angle to obtain proper fit. With any luck, the error should be all but impossible to see with the naked eye.
A picture or two would be very helpful, and some dimensions. Your 1/16" error could be huge or minor, depending on the scope of the problem. You state that it is across a 22" span .. what is the other dimension ??
You also might be able to trim the doors a bit, and add cockbeading to the opening, building it out at a slight taper, making the repair even less visible .. assuming face frame construction. If it's frameless, I think you are screwed.
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