I used to rejoice at stuff like this - like when you could get more than one chocolate bar from a vending machine because of the way they were stacked.
But in my older years I have got to wondering about the ethics of it. You wouldn't steal a pop or a chocolate bar from a convenience store, even if you were 100% sure there were no video cameras, no other customers or cops around, and you saw the only employee walk into a bathroom at the far end of the store and leave you completely unattended (and heard him doing something nasty that would surely take a long time).
So when it came to the chocolate bars, fine, I could rationalize that if I didn't take the free one that came out (maybe after an extra hip-check to the side of the machine), the next person would. But for the more obvious case of mashing buttons to intentionally get a free one, how is it different than stealing?
(BTW, I don't think I'm better than you, I've done this too - just re-visiting it mentally now)
For some reason, for myself and many others, if something is on the honour system, we would never steal from it, but the more defenses people try to put up to prevent me from getting something free, the more I want to circumvent those defenses and take something for free anyway.... it's very weird.