I'm not sure what you mean by "preserve"? I don't think it's fair to leave the highest-scoring story as the winner; we usually try to privilege the one who posted first, i.e. the true original discussion. I think the community prefers that and it provides a better incentive.

The story didn't lose front page ranking because I rolled back the clock on the original submission (the one we're currently commenting on) to put it more or less where the other submission had been.