Some teams do it, and more teams don't. Assuming your men's and women's teams were both have a shot at winning, would you use a different buggy for each because:
A) The men are faster with one buggy, the women with another.
B) The buggies are equal when raced once, but might be slower in a second race.
C) We want to give two drivers a chance to win.
D) The men's buggy is faster when raced once, but might be slower in a second race.
E) The men's buggy is faster when raced once, but we don't want to risk crashing it in the women's race.
F) The men's buggy is faster, but the driver is pushing on your women's team.
Personally, I've run into A and F, but also drivers that generally did better on their second roll of the day than the first.