People have said Amazon just throws all the same items (regardless of how it was sourced) into the same "box". Sold & Shipped by Amazon doesn't mean much, as the origin might still be a 3rd party seller's item that was thrown in with Amazon's own inventory. You just get an easier return process.
I still remember the 2 pack of ToughFans I bought from Amazon where somebody had swapped the fans inside and re-sealed the box. This is probably the same, somebody bought the 9800X3D, swapped the CPUs and made it look close enough, then returned it for full refund in a re-sealed box. I doubt their RMA department is checking things that closely, probably see a sealed box and just toss it back onto the shelf.