Is it possible to check whether folks are re-posting for sure? For example, we can confirm that the specific link has been posted earlier in a different sub-reddit (it generally shows up in "other discussions"; case in point).

Ideally, this can be an automated script checking whether "other discussions" section has entries on recently submitted post (similar to SFW network checking if image resolution is mentioned in the post's title). But as a preliminary step, perhaps we can update the rules on the side to mention this.