HR-- first of all, the Charmo race was mistimed-- we got it about a second slower, which fit a lot better.

But beyond that

a) those are not "about" distances, they are exact, meaning that the starting point is adjusted for the different rails to make them exactly a mile. So in that sense, the rail makes no difference.

b) the races had different run-ups, although not to a huge degree, and that can affect the final time somewhat.

c) the grass courses were not the same speed both days.