Payment method Gift Certificate/Coupon

Zen Cart version 1.3.9f Payment method Pay Pal.

I found an order processed by our zen cart store stating payment method as Gift Certificate/ Coupon. Every other order says Pay Pal except this one. I do not know how this happened? I never set up any gift certificate or coupon. Can someone use gift certificate not set up by admin. I am sending a copy of the email below. Can someone can shed light on this strange transaction?
website https://www.arunachala.org/bookstore

1 x Archival Films of Sri Ramana Maharshi - DVD = $20.00

Sub-Total: $20.00
United States Postal Service (1 x 0.26lbs) (First-Class Mail (2 - 5 days)):
$2.29
Total: $22.29

Delivery Address

New York, NY 10128
United States

Billing Address

New York, NY 10128
United States

Payment Method

Gift Certificate/Coupon

We never set up Gift Certificate/ Coupon offer but one customer has paid using this option. Could this be because customer used Pay Pal Bill me later option?

The following post explains how it might have happened

http://www.zen-cart.com/forum/showthread.php?t=164655

I had set cod to false but did not uninstall it. That is probably how an order was accidentally generated without any payment being made.

Arunachala:

The following post explains how it might have happened

http://www.zen-cart.com/forum/showthread.php?t=164655

I had set cod to false but did not uninstall it. That is probably how an order was accidentally generated without any payment being made.

Sorry to bring back a bit of Zombi thread, but i'm also getting this issue on two different installs, with the common payment modules only being Paypal Express (rev 1.5.0) and the bank transfer module, other modules such as the late Conor's Sagepay Direct card module and on the other site Conor's Cardsave module, no COD enabled/installed.
Both install are zen 1.5.0
Any payment modules that are not used are uninstalled.
it appears from the feedback that i can get from just the 2 customers in 6 years who've had this issue that this occurs when they select to use paypal express module by after logging in on main payments page, then it appears they encounter an issue on payment confirmation page as when they click confirm( to take them to paypal site ) instead they get sent back to cart page (wonder if becuase paypal server unavailable, not enough funds in account??) and get returned, this seems to mess up all the payment options as appratnley customer tried to pay by card and got given the order confirmation page..and order got put through without any payment being recieved.
Order comes through with payment method as GiftCert/Coupon.

Any ideas?