First of all, you should know that each person can only hold one savings card or debit card of China Merchants Bank, and each person has one card. But you can apply for multiple credit cards, so the direct answer to your question is that you already have a credit card of China Merchants Bank, and you can apply for another one.
But under normal circumstances, your new CMB credit card master card shares the credit limit with your old CMB credit card master card, that is to say, the credit limit of your CMB credit card will not increase because you add a new card. If you want to increase the credit card limit when adding a new credit card master card, remember to prepare your own financial information (it turns out to be stronger than before).