When Bad Penny is destroyed, it goes back into my (its owner's) hand. But if Yxilo Bolter destroys it due to its Fight/Reap effect, it is purged. In this case, which effect "wins"?
Destroyed effects actually trigger just before the creature leaves play, so in this case Bad Penny is safely returned to its owner's hand just before the purge would be applied. At that point, Yxilo Bolter's effect tries to purge Bad Penny, but it is considered a new object, and so the purge does not take effect. By contrast, a card like Oubliette would purge Bad Penny because it simply purges without going through the destroy flow.