You can never tell when something will become collectible. A coloring mistake in the printing, part of a stamp's artwork gets rotated by ninety degrees, and otherwise-sane ponies are shelling out thousands of bits for the honor of owning something which no longer has a practical use. But not every mistake qualifies, and so Twilight has to directly teach Rainbow the differences: some errors are just that.

The education on how to defraud the public through creating your own collectibles, however, was completely unintentional.

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