This is confusing. This is two different designs for the same thing. To sum the changes up:
- Different banner on top of the post.
- Before: banner pushed as part of post contents and can be edited.
Worth to mention the "marked as duplicate by ..." message in the bottom is the same.
Suggested fix: simply run a script that within the same transaction Reopens all questions closed as duplicates before Feb 7th 2013 then closes them again as exact duplicates. If possible prevent this from bumping the question i.e. don't update the "last activity" time stamp.