I'm assuming that posts with the intermission tag occasionally get removed, presumably when Jon or mods are looking them over for the intermission itself.

This creates a problem where two people who have the same gif could upload it at separate times, despite Jon having already accepted or rejected it.

I think that rather than removing the gif posts, there should be a separate tag for when gifs are reviewed by Jon/mods, maybe a tag for when a gif has been used on stream, or if need be perhaps even tags for whether they were accepted or rejected.

This way, gifs that are used on the intermission are archived, and when someone has a gif to submit they can search for it on the booru to prevent reposts.

Eh, I don't think that the extra tag's really necessary. Once I go through and grab GIFs, any duplicate ones I see later I'd just remove, just like when I download one and then remove it.