On Replit Ask we handle duplicate bug reports and duplicates in a unique way. If they add value we merge them into the original like on other forums but if it does not we close the duplicate and add a staff note sayings its dupe and linking to the original as a sign post (at least for the people that do search).
So every time there is a duplicate I need to go to the topic where we have the template, copy it, go to the duplicate topic paste it in then get the link to the original. If we had canned staff notes it would make it so much easer since we just need the link to the original topic then press a few buttons to get that template
As long as the feature is not added, maybe it is an alternative to edit the small post that is created when you close the topic. You have a full editor there. So you could add your template there and people reading it will find the link there