Answer: Each dollar note has a unique serial number. When the man tried to multiply a single note by putting it in that magical container the serial number for that particular note was copied as well. There's no problem if berries multiply because, in the end, they are food and we eat it. But notes are not printed by just any random person. The printing of notes has been given to specialized personnel and each note has its own unique serial number. This serial number helps to track these notes in case of thefts or fraudulent cases similar to this one. That's why I think this person got caught by the police instead of the old farmer.