The SIM API allows you to specify the window of time after a transaction is submitted during which the payment gateway checks for a duplicate transaction (based on credit card number, invoice number, amount, billing address information, transaction type, etc.) using the duplicate window field (x_duplicate_window). The value for this field can be between 0 and 28800 seconds (maximum of 8 hours).
In the event that the transaction request does not include the duplicate window field, and the payment gateway detects a duplicate transaction within the default window of two minutes, the payment gateway response will contain the response code of 3 (processing error) with a response reason code of 11 (duplicate transaction) with no additional details.
In the event that the transaction request does include the duplicate window field and value, and the payment gateway detects a duplicate transaction within the window of time specified, the payment gateway response for the duplicate transaction will include the response code and response reason code listed above, as well as information about the original transaction (as outlined below).
If the original transaction was declined, and a value was passed in the duplicate window field, the payment gateway response for the duplicate transaction will include the following information for the original transaction:
The AVS result
The CCV result
The Transaction ID
The MD5 hash (if this feature was used for the original transaction)
If the original transaction was approved, and a value was passed in the duplicate window field, the payment gateway response will also include the authorization code for the original transaction. All duplicate transactions submitted after the duplicate window, whether specified in the transaction request or after the payment gateway's default two-minute duplicate window, are processed normally.