Can you explain to me what you mean by "joined to antennas"? Can I use a splitter in reverse, or do I just splice the wires, or what?
I am close to the city of Chicago, and found when I downgraded from a rooftop antenna to a little rectangular guy, the antenna was much less finicky, but I still have trouble where CBS, ABC and FOX never all work at once, I have to shift it slightly, and I wonder if I bought a second one and aimed in the second direction, if they would fight each other or work together.
In general you CANNOT join two antennas. You would be creating Multipath and usually have unpleasant results.
The exception is combining a UHF only antenna and a VHF only antenna with a combiner specially designed to do that.
I suggest that you look up your TVFool results and post the link on:
The Official AVS Antenna and Related Hardware Topic! - AVS Forum
The folks there may be able to help you. Your question is OT here.