As of this writing, the question "Why certain variables are used in “hotness” calculations?" appears to be on both SO and Meta. Its question-history on SO as well as the "migrated from stackoverflow.com" line on Meta appear to indicate that the question had been migrated from SO to Meta at one point. Yet, the question is still 'open' on both sites: it appears that Jeff Atwood has reopened the question on SO.
Further, the question's only answer has had different destinies on each site: it has different edit histories, different vote-counts, and is accepted on Meta but not on SO.
How is all of this possible? Is it acceptable for a question to be migrated to another site yet still be 'open' on the original site? How is the 'parallel' existence of the question managed in such cases?