Cannot find out when applying for a credit card. However, the public security organs can detect them through portrait comparisons. Now many provinces have begun to compare people, and it is said that nationwide comparisons will be carried out soon. You must cancel one of the dual accounts, so you'd better not use both to avoid a lot of trouble if one is canceled. Of course, the best way is to cancel one as soon as possible, otherwise after being found out, you will not be able to decide which one to cancel