How can I duplicate a whole topic?

[codinghorror (Jeff Atwood)]

Well, you can search for the definition of topic in Google:

top·ic
/ˈtäpik/
a matter dealt with in a text, discourse, or conversation; a subject.

It’s quite accurate. If you prefer a different word for personal reasons you are free to edit the text in Discourse via Admin, Customize.

As far as the original matter..

@Cécile_Savoie

The reason I needed to do it this time was because someone created a topic with a very long title that could be interpreted in two different topic threads. We (moderators) noted the issue of long title (this will be restricted to less characters now) but didn’t realize at that time that it would cause a problem.

The conversation started and before we knew it, we had two very intertwined delicate conversations going on, with some offensive comments from one member that nevertheless provoked a rich series of responses in both matters.

Why not press the admin wrench on the topic and split the topic, so the replies about the “other” topic are in a different, but linked topic? That would be the simpler course of action, supported by a whole host of tools in Discourse.