Many RTV affiliates are on digital subchannels, or at least are part of a duopoly with another station. Dish probably advertised with the main station and the main station probably has a special deal for advertisers if they want to pay a little more to run their ads on both the .1 and .2 channels. Just a guess. I've noticed that locally, a lot of the subchannels, RTV included, run the exact same ads as the main channels, filling in the unused ad blocks with PSAs and promos for the main station's news departments or prime-time lineups.