For almost two years now, we've had extensive support for preventing editing conflicts. That system makes it impossible for attributes (like an episode's name or airdate) to be repeatedly changed back and forth, thus preventing edit wars.
But one thing that it doesn't cover is incorrect entries being deleted altogether, only to be re-added in the exact same form later on. But as of today, that'll be prevented as well! Before allowing a new entry to be created, this new system will extract the entry's "primary attributes" and check if an entry with those same attributes already existed in the past.
For example, for a Show Cast the primary attributes are the referenced Person and Character. If you try to add a new Show Cast, when a Cast entry for that Show referencing exactly the same Person & Character already existed in the past, the attempt will be blocked.
Of course it's possible that an entry is deleted incorrectly and it has to be re-created, so there are exemptions for some users: Trusted Contributors can re-create entries one single time, while Curating Contributors and up can do so indefinitely.
Right now the system is enabled only for Show Cast; if there are no bugs it'll soon be enabled for Show Crew, Guest Cast, Guest Crew and Episodes as well.
If you do notice any bugs or have comments/questions in general, feel free to ask :)
