This article covers
How to move payment methods from one customer to another?
As a first option, we can make use of our, 'merge customers' bulk operation to merge the customer records, you can learn more about it here
This action moves the source ('from') customer's payment methods, subscriptions, invoices, credit notes, transactions, unbilled charges, and orders to the target ('to') customer
Chargebee does not store any raw payment method details with us. All the payment method details are saved to the respective gateway vault. The gateway will pass the reference ID of the payment gateway after creating and tokenizing the payment method.
Though you will be able to add a new payment method to the account of customer B by taking the reference ID of the payment methods of customer A. But the customer details in the gateway will still carry the information of Customer A linked to it. which can cause issues related to mandate, address and other information validation and can end up with transaction failure.
Hence there is only one way and that would be, Customer B adding the payment method freshly to his account. Though raw card details will be the same, the reference ID and mandate details will be different entirely.