Both Visa (82) and MasterCard (4834) use special Reason Codes to designate chargebacks issued when the same transaction is deposited more than once....
Reason Codes 76 (used by Visa) and 4850 (MasterCard) designate chargebacks resulting when a credit is posted on a cardholder's account as a purchase....
Merchants should monitor their average transaction amount and count in each credit card batch and alert their processor if either is substantially exceeded....