I think the counterfeiters simply assumed incorrectly that the Peruvian mint makes new coins on an annual basis. They did not put in the year of the coin they w

I think the counterfeiters simply assumed incorrectly that the Peruvian mint makes new coins on an annual basis. They did not put in the year of the coin they were copying because their coins would be brand new and shiny and it would be suspicious to see old coins being so new. They simply put in the year of the counterfeit or even a future year based on planned release of the counterfeit coins. The counterfeiting was probably done in the US or Europe. The nickel silver process was not known in Peru at the time and Peru is a small country so it is doubtful someone could start minting coins using new equipment and a novel process without the information getting out. But somewhere faraway in the US or Europe somebody could use an existing mill to mint some obscure foreign coins without even the workers suspecting it is illegal. The counterfeiter can say he has a contract to make the coins from the Peruvian government and I doubt anyone would have raised an eyebrow. Thus, the counterfeiter probably did not have good information about the Peruvian mint's plans to mint that particular coin that particular year. As far as the banks, no counterfeiter shows up at a bank with a roll of their fake currency. Bankers are trained to recognize fakes. The counterfeiter would try to place it in the stream of trade, so that by the time they reach a bank the fake coins are mixed with real coins and are submitted by a trusted customer. The counterfeiter would probably go to a port town find some poor and suspicious looking merchants and use the fake coins to buy some peruvian goods at somewhat generous prices.