Would it make sense for HN to do something like the following? Pull link out of submission and check database to see if that link has already been submitted. I

Would it make sense for HN to do something like the following? Pull link out of submission and check database to see if that link has already been submitted. If it has, either automatically insert a comment containing links to the older discussion(s) OR append those links to the post itself? It's going to be fairly brittle, because you're only comparing the addresses and not the values stored, but it seems like it wouldn't need too much work. Anyone have any thoughts?