Right click on a file in the sidebar and duplicate it

How would this be superior to left clicking the file in the sidebar to get the file in context and using 'Save As' to create a duplicate?

Not saying your idea is bad. Just giving you the chance to expand on it to 'sell' the idea to the community so we can see what new and added value it adds over what we have. There are so many good ideas in here that getting up votes is hard unless you make it obvious why your idea deserves them.

https://github.com/titoBouzout/SideBarEnhancements/ - "Add to the command palette useful commands as duplicate"

You can add commands and customize the right-click context menu for projects via "Side Bar.sublme-menu" file.

Thank you @robertcollier4, that was exactly what I was looking for.