They don't enforce this at my local store. They had this same deal back in November. I bought 2 of them for 130 a piece at the same time. Even if they did try to enforce you can just do multiple transactions. None of the employees will care. This isn't even that crazy of a deal for MC. These have been $150 or less at MC for months. Just one more reason to think Zen 2 is going to be a game changer.
The 2700 is $200, comes with a cooler, and will run at the same all core turbo stock with higher IPC. The only way the 1700x makes sense is with a $30 tower cooler overclocked to 3.7-3.9 ghz IMO. If you are going to spend $100 on a cooler for it you'd be better off with the 2700 and a $30 tower cooler. Or just buy the 1600 for $80 to tide you over until black friday month when Ryzen 3000 will be widely available and hopefully discounted. I wouldn't be surprised to see dirt cheap second gen at that time as well. Either way don't run out and buy anything until after the AMD keynote on Monday.