It doesn't happen often, but it can occur. This situation typically arises when the batch (end of day) process is not performed daily and the batch (end of day) process is instead initiated from the bank's system. If the batch containing the POS transactions has already been closed on the bank side, and a batch (end of day) is manually triggered from the POS without checking whether the relevant batch is closed in the authorization system before processing the batch close request coming from the POS, the related transactions may be posted to the merchant account twice.
To prevent this situation and keep the process running properly:
- When a batch close request comes in from the POS, the bank's authorization system should check whether the relevant batch is already closed; if it is closed, the previously matched transactions should not be transferred to the merchant account again.
- If there are transactions not yet in the authorization system that are transmitted during the POS batch close (for example, offline transactions), these transactions should also be reflected in the merchant accounts.
- Even if the relevant batch is already closed, a successful batch close response should still be returned to the POS for batch close requests coming from the POS, and the batch number on the POS must match the batch number in the bank's authorization system.
