With this, you could invent a very unique magic trick where your spectator well-shuffles a deck of cards, then you can secretly swap your deck with one of the decks from your collection to reveal that yours was shuffled in the exact same way.
This is a relatively well known technique in card manipulations known as a "cold deck". There are many variations of it involving probabilistic but not entirely deterministic forces that lead to a branching path to a different cold deck.
vunderba|1 year ago