Well, that's what the Auction House says ( Antiquorum ). What is the detail which makes them think that it is a prototype? The nipple dials, here. Which you don't find in any other Explorer II, 16550 or 16570. Now, I am very prudent when it comes to Rolex...
You're right Bill, Rolex is very hush and secure yet Rinaldi keeps on releasing these with their "partners" Antiquorum and the Mondani family. Looks like they took the indices from a GMT nipple dial and pasted it onto an Ex.2 dial and it's now breaking ne...
If there's no evidence you should pass. Unfortunately there are cases of high elaborated stories , with faked provenance , ..., making some objects as one chance in a life time, and with a huge premium on it! And this is sad....