In fact, the main difference between a set of two cards and a dual-currency card is that the card issuers are separated, that is, there is only one card issuer, such as UnionPay, MasterCard and Visa. When using, a set of two cards, each card has only one card issuer, so it can only be used on machines with corresponding card issuers, which is a little inconvenient to carry. Dual-currency card is an earlier card type, and one card has two card issuers. At present, the international practice is that one card corresponds to one card organization. Previously, dual-currency cards issued in China were jointly promoted and issued by MasterCard, Visa and UnionPay.