The limit of two souvenirs per visitor is interesting, perhaps they imagined someone would try this. The trick, then, is to collude with other souvenir purchas

The limit of two souvenirs per visitor is interesting, perhaps they imagined someone would try this. The trick, then, is to collude with other souvenir purchasers, similar to McDonald's Monopoly, so you can quickly swap your own duplicate pieces to others who need them. But unlike Mcdonald's Monopoly, there's probably no rare Park Place that virtually guarantees an instant win to whoever holds it. The bank could do something like that. They could cut all the bills in two, and incinerate the left 60% of every single bill, so the souvenirs only contain shreds of the right 40%, thus guaranteeing that nobody can ever reconstruct 51% of a bill no matter how many souvenirs they have. But there seems to be no evidence that they're doing this.