The referenced posting gives the following explanation;
"HIP HIP HOORAY!!! We have LENDER'S APPROVAL for SHORT SALE at this NEW LIST PRICE!!!! Don't delay, call today and this nearly new custom home on 1.3 acres in Penryn can be yours!!! Home to be sold AS-IS"
Without further investigation, my opinion is that the first pricing at $499K and the second pricing at $475 were not approved by the lender. They don't have to be, just to list it. A seller can list their house for any price they want, ridiculously high or ridiculously low if their agent agrees to list it for the price.
Since short sales cannot close escrow and transfer to a new buyer without the lenders approval, any price other than what the bank eventually approves is meaningless. The act of placing a list price on it at all, then becomes a tool for sellers and agents to use to invite people to look at the house and to make an offer in order to goad the bank into making some kind of counter offer... Until they get an offer on a short sale house the seller and their agent often have no idea whether the bank will ever cooperate to sell the house at value, much less a discount from value. Since the bank won't tell the seller or the listing agent what they will accept, the sellers and agents often list the properties artificially low in order to draw in offer that will then establish the price. The first offer (Especially if it is low) is kind of like bait, thrown out to be sacrificed to a higher offer that is expected to come along once the bank has shown its cards and revealed how much of a hit they are really willing to take