What do you mean by two postal credit cards? What's the difference? Do it for the first time.
Your two cards have different signs, and the network for credit card consumption is also different. One card belongs to UnionPay, which is mainly used for credit card consumption in China. The other card is MasterCard, which is mainly used for overseas credit card consumption (the acceptance of overseas UnionPay is not high), and the two cards share a quota. In addition, don't put all the credit card numbers online like this, which will lead to information leakage.