Interesting thing happened at DG doing serve load today. Did a single OVVGC and for some reason the transaction failed after drawing the money off my GC. Register said $500 due to customer. Clerk wanted me to swipe VGC again, but I elected to swipe my real debit card instead. I checked before leaving the store that it was in my bank account. Knocked off a step

Not worth the hassle to do intentionally though.
I should add, I'm tempted to replace my debit card now that it has been swiped at DG.
Not sure why it didn't process correctly. GC was drained; it now shows a $0 balance. And the money was loaded to serve (shows on the transaction list and I got the email,) and then reversed.