Why share the karma? They submitted a dupe -- if anything, it should have redirected to the already posted one...12+ hrs is a long time. (I understand it's a delicate dance between surfacing unnoticed posts and OC)
We direct for the first 8 hours, I think. After that we only redirect if the earlier post got significant attention. The trick, as you say, is to find a balance that gives good stories multiple cracks at the bat—it's much worse to miss out on a good story than it is to have a few reposts.
