The linked article refers to two dissimilar antennas linked by #12 AWG electrical wire that looks like it is still in the original 2/3 conductor sheath. #12 AWG electrical wire is a disaster at TV frequencies. It's nowhere near the correct impedance, will have excessive SWR and may have dielectric losses.
That article is a perfect example of how not to install two antennas. The two antennas are dissimilar, too close together, not joined properly and pointed in different directions. The poster just got lucky and probably benefits from having strong, non-interfering signals in both directions.
p.s. I can get two channels with a paper clip. It doesn't mean it's a good TV antenna.