If the tivo's will accept 2 Tv antennas / inputs on the tivo's / Do the tivo's have 2 tuners in the tivo's ??
Run a separate coaxes for the antennas.
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You can try a Winegard CC7870 (Hybrid) transformer coupled antenna combiner.
http://www.winegarddirect.com.
http://www.solidsignal.com.
http://www.amazon.com.
If one of the receiving antennas has a separate matching transformer balun , reversing the 300 ohm transformer antenna connection leads at the antenna will sometimes help with antenna signal phasing of the 2 antennas.
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Another way to do it is , run coaxes from each antenna to the Tv / Tivo locations and use remote control A/B antenna switches.
http://www.mcmelectronics.com. #32-4425
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The jointena's , are discontinued and are limited to remaining stock.
I do not see a channel 43.