It looks like matches between two members of one clan apply for all the other clans they are in as well as the global leaderboard. This could mean that the clans you are in could have an effect on the matchups in global matches, especially when simulating. (It says "You will mainly help simulate games for allied players in your clans and courses.")
Three days ago I was matched with the same member of my clan 11 times. Matchups between the same person's hero/ogre opponents might also be more common.