This is the revision history of a post that was closed as a duplicate then reopened, here on Meta. Note that there is no part of the revision which mentions or links to the alleged duplicate:
The Community user used to edit in a block that explained it was closed as a dupe and had links to each question. It was sort of a hack, since it was part of the post's text, which was still editable. But in removing that hack, we lose the link to the possible duplicate.
Sort of but not quite related to "Duplicate of" banner and link to duplicate removed when a post has reopen votes, there's no revision of the closure. The banners appear/disappear as proper now, but now after reopening there's no evidence this post was ever closed as a duplicate.
I really think the revision history should keep a log of what question(s) a post was closed was a duplicate of. It could be it's own revision or kept as part of the post closed as duplicate "revision".