card clash

This is what happens when you wave your whole cardholder, be that a wallet or a purse, at the screen to tap on or tap off a bus or train. The reading device can pick up one contactless credit or debit card as you tap on, and then a different card as you tap off. The result is that you are charged for the whole trip twice, once on each card.

 It was given the name card clash by the TFL (Transport for London) but as the new technology is being rolled out on our transport system as well, we are being introduced to the notion.