I can see how that might go wrong in the USA where all their notes are the same size, but in the UK I'd have expected the physical size of the note carriers to prevent fitting a £20 cassette in a £10 slot.
Happens reasonably regularly. You get a stroppy letter from the bank asking for it back; keeping it is "stealing by finding".
t.
Simpler to make the carriers one size so you don't have to make different ones for virtually every country. Then have adjustable guides to position the notes correctly. Like the guides in printer paper trays.
It would also be simple to have probe(s) attached to the guide(s) that project into the machine that has a fixed plate with hole(s) in the right place for the probe(s) of that holders denomination.
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