I imagine that so long as they are competing against one another in bidding, they would cut down to exactly the least each believes they need to barely scratch out a win. Otherwise as soon as I bid 3:1, someone will offer 2.9:1, and we are still off to the races.
This results in something like 'wargamer fair fights'. Which is both befitting the clan ethos, and at odds with it - because challenging an IS HBK-G to 'duel' on a featureless plain, while driving a Puma Prime, and then promising to do it with only one PPC, strikes me as a very clan thing to do. Honorable even, because if that Stravag Inner Sphere Dog was a -real- warrior, he would have enough speed and range to fight back.