Aircraft patrol defensive damage is way too low

I was doing some patrol tests to evaluate the following claim in the wiki:

• "If 2 enemy aircrafts patrol in the same area with overlapping patrol circles, they attack each other as well, while also returning defence damage to the other plane. In such a case the applied damage depends on the size of the area that is overlapping, with full damage only being applied if more than half of the circle areas overlap."

I tested two interceptors at 3 overlaps 1) outer edges just overlapping, 2) half overlap where patrol radii just covered the position of the enemy plane and 3) perfectly superimposed patrol radii. For the attack damage I did not observe any variance with patrol overlap and the attack damage values were as expected. For defensive damage there did seem to be less damage with the least overlap, but for all overlaps the defensive damage was well below the expected damage - 20%. I also tested it with a tac bomber attacking and an interceptor defending and the interceptors defensive damage was again well below what would be expected.