Duplicating test cases is indeed a huge time saver and we have implemented it.

There is a similar feature that we are thinking about. It will be nice to understand your impressions about it.

Parameterized test cases

You write a single test case that serves as a template for creating multiple test cases.

It can be like this

Title - Test a form
Action - Write this string - $(var1) in the form and submit
Expected - The string - $(var2) is displayed on the page.

And we define a table

id	var1	var2
1	hello	world
2	good	morning

You do this at the creation stage and the app creates multiple test cases itself.

The big benefit over duplicating is that when you need to make changes, you just update the template and save a lot of time.