For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
Could be original and done when there were production shortages. I have had 820-2915 boards with 6490m GPU but fully populated VRAM on the board. Back in the 2008 days you would even find the red solder mask engineering boards in production machines.
I also had iPad 2 housings with the plastic top for cellular, but without a SIM slot and no way to fit a cellular board in it. Some weird shit is floating around probably from prototypes and/or engineering samples.