In your version, it seems like there was a third player in the mix. The two players making the choice were provided with a shared opponent who is trying to take both their chocolate for himself. Could this mean that in situations where two players share a threat, they're likely to team up and mutually acquire a win rather than give the source of the threat everything? So, let's see... by playing black on each other, they mutually played red on you. After all, they both chose to leave you entirely chocolate-less.
That's brutal. ;)
But yeah, the stakes were pretty low. Then again, women do get crazy over chocolate. Also, it was a big chocolate, so maybe they were both happy with half? On a diet but didn't want to cheat "too" much? Make you think they eat responsibly or are a "nice" person to impress you, because they like you? I need to see more trials. :)