Is it possible that the base price were for different room types? Using the publicly available promo, I've only seen King Bed rooms at POR as part of the discount for the dates I was looking but without the discount they had all room types available.
It was the same room type. I did it for 3 different resorts about 5 times each and cleared cache.
Bottom line is you're not really getting 20% off of a price you could get.