Marshmud: Actually it does look like a bug, the S-B should be 33 for both. Ratings don't matter for the S-B.

S-B is just you add the points for each win they have.

Each players had 1 win against a player that had 9 points.(x1 = 9 points)
Each player had 2 wins against a player that had 6 points (x2 = 12 points)
Each player had 2 wins against a player that had 4 points (x2 = 8 points)
Each player had 2 wins against a player that had 0 points (x2 = 0 points)
Each player had 2 wins against a player that had 2 points (x2 = 4 points)

So each player should have ended up with a 33 S-B rating.