There was one set of reports, sure, but the set contained 989 measurements of the signals from each antenna! Somehow I think that means more than one experiment iteration, which would suggest one report on each antenna.
It is far more conclusive than the usual method used, ie. a bloke on the radio saying one of your antennas moved his S meter a bit more than the other one. Using the DSP inherent in the WSPR software to compare two signals received in the same 110 second period has to be more rigorous than the S meter method so often relied upon by the popular e-forum reviews.
When theory predicts the vertical has a lower angle of radiation and therefore at a "dx distance" will have probably had fewer hops and hence lower loss than the signal from another antenna, I think it's worth considering. I have used that theoretical prediction for the last 50 years to good effect. With these measurements we start to see the practical, empirical measurements confirming the theory.
As stated earlier, I like this experimental approach and hope Richard has time to do more of it. It's a great application of the tools, combined with the neat WSPRlite signal sources.
73 Andrew VK1DA VK2UH