Why are there duplicate payments?

How duplicate payments are created

When a payment request is received, Adyen doesn’t check the merchant reference for uniqueness. This means that a shopper can open multiple payment sessions during checkout and pay in all opened sessions. A shopper, for example, can open and pay in multiple tabs in their browser.

On your system, these sessions have most likely the same merchant reference. However, Adyen's system sees them as unique payment requests, and creates a unique PSP reference for each of the sessions, causing duplicate payments.

Duplicate payments can’t always be prevented. However, API idempotency can be an option to help avoid them. 

Pending authorization 

In some cases, shoppers may see two separate pending charges on their bank statement. The issue is quite common when the authorisation and the capture are done separately in a payment. Therefore, the double charge that shoppers see is most likely an authorisation (pending charge), rather than a real charge.

For clarity, duplicate charges should produce 2 unique PSP references in our system. If you only see 1 transaction linked to the charges claimed by the shopper, it is very likely that bank display is not correct.

With regards to the pending charge, this should be automatically cancelled in about 4-5 working days depending on how fast the bank updates these charges. 

Shoppers can contact their bank to cancel the pending charge or correct the transaction display that is being shown wrongly in their bank account.

How to manage duplicate payments

There are two types of duplicate payments. 

• Duplicate payment on two separate PSP references: After checking there is indeed a double charge, we recommend you to send a refund. The transaction should be refunded according to the settlement delay.
• Duplicate payment on a single PSP reference: We recommend you to reach out to Support who will check the payment history and take care of the refund.