Why does a customer have more than one card on their Customer Summary page?

A customer ID that shows multiple cards associated with it, is due to the customer adding their card to multiple devices such as a mobile phone or smart watch. When a card is added to Apple Pay or Google Pay, the long card number is changed for security reasons and is treated as a brand new card when a transaction is processed with alternate payment method. 

When Littlepay attempts to authorise a transaction with the issuing bank, within the messahe response is a Payment Account Reference (PAR) which helps to identify if the customer is using the same card via a mobile device.

The PAR is then matched against other transactions that have been previously processed and groups them together under one customer ID.