Thanks for the comment, Jeff. I can confirm that yes, these edits are more than 5 minutes apart. But even if they weren’t, as long as a single post_revision gets created, shouldn’t there ALWAYS be an accompanying EDIT user_action?
As a side note, I also tried changing the editing grace period to 0 and when I do that, 2 identical post_revisions are created for every change. I don’t know if this is by design or if it’s an unrelated bug.