I BOUGHT A DISH500 AND IT WAS SUPPOSE TO COME WITH DISH PRO TWIN. BUT IT CAME WITH TWO DUAL. NOW THE RETAILER WANT ME TO BUY A DISH NETWORK TWIN(LOOKS LIKE LEGACY TWIN) WHAT IS THE DIFFERENCE BETWEEN DISH PRO TWIN AND A LEGACY TWIN. WOULD I BE BETTER TO STICK WITH THE TWO DUALS. HELP NEEDED ON THIS. WILL USE THIS DISH WITH A VIEWSAT ULTRA THANKS MLS