no, different card numbers have different names, so you can set different passwords and payment methods (signature payment/password+signature double insurance). However, the record of consumption will be displayed in the main card bill, and the repayment of two cards is also completed by returning the main card bill. Therefore, you can also choose to use the main card to associate with a peer UnionPay card to automatically remit the repayment. It can be said that it is relatively independent to use, but the repayment operation is also very convenient. I just use the main card of China Merchants Bank, the supplementary card that my mother applied for, and the UnionPay card associated with my peers will automatically repay when it expires. Because UnionPay card is a salary card, I don't have to worry about forgetting to repay when I work overtime, and I don't have to worry about how many cents I will spend in my credit card, which is quite convenient. These are my practical experiences and feelings, and I hope I can help you. In addition, the available quota refers to the quota of main card+supplementary card, that is, if your original quota of main card is 1W, then after applying for supplementary card, the quota of main card+supplementary card will be 1W. However, China Merchants Bank will increase its quota very quickly. You can also apply for an increase in the quota on your own initiative. If the bank approves it, you don't have to worry about the shortage of the quota for two people.