[timgr]

It would be fairly involved to mix the signals on the same band so they could be separated at the tuner. The digital signals are already time-multiplexed into each frequency. So you'd need to separate the two streams by frequency. That involves a frequency generator and mixer to make sidebands at a new frequency. Then one of the sidebands could be filtered from the stream at the other end and mixed down to the proper frequency for your tuner. Not impossible, but any antenna-based solution is going to be vastly cheaper, I'd think.

A simpler solution would be to filter the stream from each antenna to only pass the single channel or channels that you want - effectively making a narrow-band antenna. Then you could mix these streams on the same wire and they would not interfere. Still, it's going to be more expensive than a DB8e, for example, that could be pointed in two directions.

Yes, you can put the UHF/VHF signal into the UHF port, but only UHF will come out. The preamp filters out VHF from the UHF input, and vice-versa.