How far away are you from the stations and what’s your general signal strength? You may be able to do something more omni directional, but really depends.
Each channel is on a different frequency. All the frequencies are there all the time and you just tune in to the one you want. I guess the question would be with two channels receiving the same frequency and then being connected together cause some sort of phase shift or something. I wouldn't think so but I knew an antenna design engineer once and even he said that building antennas is kind of a black magic/trial and error sort of process. If they are connected together, you don't have two antennas, you have one in the shape of two. Without having a good understanding of it, I would guess that it won't work because if it did you wouldn't have been the first person to think of it.
You guys are all thinking new technology! I'm assuming these antennas use coax cables? I don't see why you couldn't have them connect into one of those old A-B switches that we used to need to connect the Atari to the TV, and just switch between the two depending upon the channel you want. You could even label the A and B sides with which channels are for which button. Assuming your Mom? Grandma? I forget, are ok with hitting the switch, there is no reason that wouldn't work.
