The CBILL scheme has no checks and no constraints on submitted payments, so the payment is executed each time a POST Create_CBILL_Order is executed. For this reason, it is recommended to rely on the Validate_CBILL_Order API response that restores the status of the payment before executing it again.
In the case of multiple payments of the same CBILL, it is necessary to contact directly the entity to which the payment was made in order to arrange for re-crediting.