No, it only affects the amount of items and gold dropped from certain creatures, it improves from 2 to 5 the chances to drop from each creature, which will count as twice the loot on each creature you kill. The skinning doesn't count since you're not getting loot from a creature you're just using a different feature. I don't know and I don't remember but I believe there was a world event where successfully skinning a creature chances were improved by a certain percentage, but I'm not sure of this. There's no record on double loot giving more chances of skinning.