Response Reason Code: 11

Response Reason Text: A duplicate transaction has been submitted.

Notes: A transaction with identical amount and credit card information was submitted within the Duplicate Transaction Window.

The error indicates that a transaction request was submitted within a few minutes of a previous attempt with the same information. Authorize.net identifies duplicate transactions by matching the data provided with the transaction.

The data fields that are validated are:

• API Login ID (x_login)
• Credit Card Number (x_card_num)
• Expiration Date (x_exp_date)
• Transaction Type (x_type)
• Bank Account Number (x_bank_acct_num)
• Routing Number (x_bank_aba_code)
• Purchase Order Number (x_po_num)
• Amount (x_amount)
• Invoice Number (x_invoice_num)
• Customer ID (x_cust_id)
• First Name (x_first_name)
• Last Name (x_last_name)
• Company (x_company)
• Address (x_address)
• City (x_city)
• State (x_state)
• Postal Code (x_zip)
• Country (x_country)
• Duplicate Window (x_duplicate_window)

If any of the fields change from one transaction to the next, Authorize.net will not view the transactions as duplicates.

The duplicate transaction window will always be two minutes for all transactions submitted through the Virtual Terminal. If you wish to adjust the duplicate transaction window for transactions submitted from your software, such as a website or shopping cart, you may do so by adding the field x_duplicate_window to your website script.

If you are unable to adjust or add this variable to your shopping cart settings, please contact your shopping cart support team for additional assistance in this regard. The variable x_duplicate_window tells us, in seconds, how much time we should check for duplicates after a transaction is submitted.

The largest value we will accept for x_duplicate_window is 28800, which equals eight hours. If a value greater than 28800 sent, the payment gateway will default to 28800. If x_duplicate_window is set to 0 or to a negative number, no duplicate transaction window will be enforced for your software's transactions. If no value is sent, the default value of 120 (two minutes) would be used.

For example, if you wished to set a duplicate transaction window of five minutes, you would set x_duplicate_window to 300, as there are 300 seconds in five minutes.

Note: By submitting x_duplicate_window with your online transactions, we will return further details along with this error response, including:

• The original transaction ID that was duplicated;
• AVS and CVV responses for the original transaction;
• The original authorization code, if the transaction was authorized;
• The MD5 hash, if a MD5 hash value was generated for the original transaction.

If you do not submit the x_duplicate_window field, we will not return any details from the original transaction, even if you submit a duplicate transaction.