May want to edit the details on both boards to reflect what they actually are. There are 2 x99 Deluxe boards and and 2 x99 Pro boards your pics show you have the newer versions but the description is the older version.
Just need to add the end after Deluxe/Pro really. ASUS X99-PRO/U3.1 vs ASUS X99-PRO ASUS X99-DELUXE/U3.1 vs ASUS X99-DELUXE
The older models were replaced with the USB 3.1 versions so they are fresh and cost more which justifies your pricing. People may question your pricing with the details not actually saying the new model numbers of the boards with possibly overlooking the actual pics and noticing they are the 3.1 versions.
Just trying to save you some headaches.
Just FYI for those that don't know ASUS runs warranty off serial so having a proof of purchase doesn't matter they don't ask for it. They are one of the few companies that actually stand behind their product and don't jack you out of a product warranty if you aren't the original buyer.
No problem. You may want to edit the OP though with the addition to the model number. Not everyone will look at the pics. The 3.1 are the newest versions and are also more expensive.