Hi,
most likely a rounding / mathematical issue. Precisely why are the displayed numbers not identical can be probably only be answered by a software engineer from the OPF provider.
regards, FD
PS: it is often hard to see from an OPF whether the displayed data (wind, temp, MORA, speed) is valid for a waypoint or for the leg between the waypoints. Could be the case here, that you are looking at two different physical places.