Abstract: A system and method for securely authenticating a dual number payment card used in a purchase order is provided. A request to approve the purchase order is received from a cardholder that owns the dual number payment card, via a first path. The request includes a site address of a website, an order number and a second card number of the dual number payment card. A first card number of the dual number payment card, associated with the order number, is received from the website, via a second path. A matching pair of numbers that identifies a stored dual number payment card, is searched in a card details storage. If a first number of the matching pair matches the first card number and a second number of the matching pair matches the second card number; the purchase order is approved.