Would it be possible for you to preserve the highest-scoring dupe when you do this? I was reading through one of them with around 350-400 points, and now I can't find it but this has around 100. It makes it unclear that it's the same original discussion moved, and I doubt this was your intention, but it could come across like you're trying to downplay the significance of a topic when the main discussion loses points and frontpage ranking.
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.