by PzVIE
This is not only a Repos problem. Printers often aren't able to match a card back exactly, when asked to do a second print run or an expansion set - which could lead to a problem in the latter case.I have no idea why this is so - maybe a fellow gamer working in this kind of industry can tell us more here (although mankind has even landed on the moon - and more than forty years later they still aren't even to print two identical tones of purple ...? Suckers!)
However, a solution to this would be that producers use a different kind of card backs. A good example is this (the image shows only the cover, but the top portion of it is identical to the card back):
Even if the card becomes dirty or bended, it is very hard to spot. And I have more than one card packs from print runs several years apart, and you can't tell the difference.
The drawback here is, it is ... erm ... mildly put ... ugly.