Cash app account ask for an email address and a mobile number which is registered with your bank account. You can use only one account on your smartphone. If you want to use more than one account, then you have an alternative email address and mobile number and also a smartphone. If you are not able to use 2 cash app accounts on your smartphone,then make sure you are connected with the strong internet connection and user’s credentials are correct. If you still unable to resolve it, then use Cash app customer service.