Problem in ordering

Hello I was about to order a DVD but then I saw that when I click DVD + download it says a price and when I click Download only has a lower price , tough when I go to0 pay for DVD + download I can pick up a "download only" selection under the shipment methods and the price remains unaltered compared to the Download only , why this if I check this option I get the same the dvd at 0 exp price or what?