Banner above topic for Duplicate Topics

[codergautam (gautam)]

One of the discourse forums I’m in has a feature where duplicate topics have a banner on top of them with a link to the original topic:

Is this a custom plugin? Can something like this be implemented on any Discourse forum, say letting mods mark a topic as duplicate and specifying another topic.

Thanks!

[twofoursixeight]

This is a staff notice. To add this, click on the wrench and click this button:

Then, add whatever you want.
You can put this anywhere.