shredium on 29. Jun. 2017.
If only Cho or Gall alone are uploading the replay, they are still uploading the replay of a game in which they both are taking place, so they both are being calculated anyway.
So real reason of Cho and Gall having different winrates is that statistica are included only for those who have reached at least hero level 5. There are rumors that disconnects without reconnects are also taken into account.