Godobe, I noticed the same thing and other then the different testing methodologies used between the HV10 & HV20, I can't explain it. It surely wouldn't be the first time a CCI review has some puzzling numbers.
However, after first testing the zoom/focus on my new HV20, I proceeded to do outdoor A/B testing of both the HV10 and HV20. As hard as I tried, on my 50" Fujitsu plasma, I could see no difference in detail. In fact, I think Canon has the default sharpness of the HV20 up a tad higher than the HV10. I always kept my HV10 at +1 on the sharpness. I was able to do this because the noise on the HV10 was so so low, you could extract even more sharpness without any increase in apparent noise.
The HV20 at +1 seems to me a bit sharper than the HV10 at +1, but I see no additional detail....or less detail for that matter. In reality Godobe, the pictures are so close, I doubt I could tell which was which in a blind A/B test. But in low light I certainly could!