It was discovered that when voiding a credit card payment (initiated through the Zuora UI in this specific circumstance) does not produce the intended results in the WorldPay Gateway. The payment is set to voided status in Zuora, but the payment is not actually voided if the payment is in captured status (which happens very quickly) with WorldPay.
Link to support ticket with more details on the matter: https://support.zuora.com/hc/en-us/requests/114267
