Sometime in the last day or so, the Community-created revisions that add the "Possible Duplicate" box to posts closed as duplicates started showing up on the post itself as edits by the owner. For example, on the post Sign on separate line in vote count for low-score mod nominations
The edit by Simon Brown was actually by Community, and shows up correctly in the revision history. The same thing happened on this post 5 hours ago, and this SO post 2 hours ago. These two SO posts that both closed yesterday are correct (they show no revision on the main page, and Community in the history)