If a transaction is submitted that matches a previously "Approved" transaction based on the Duplicate Checking criteria enabled for the device, then Portico rejects the message and returns a Gateway Response of "02 - Transaction was rejected because it is a duplicate."

The device may be configured to receive details about the original duplicate transaction, such as the Original Gateway Txn Id, Authorization Code, and Reference Number.  Refer to AdditionalDuplicateData, in the header of the transaction response.