Depending on how those antennas perform, you might be setting yourself up for a multipath nightmare (although the as-yet-to-come 5th generation LG chipsets might be able to deal with it).

You might want to look into a filter that will ONLY pass a single channel - so you'd add in 20 from that antenna and reject everything else it picks up. Only problem with that is you'd also reject 24, 53, 66 and any future CN Tower stations.

[Link: lindsayelec.com]