Go to any project > Find the 3 dot menu to the left of the project title > Click on 'Duplicate project'.
It will create a clone of the Project you can then rename (if you want to).
Now that the Project is cloned, it can be moved.
Learn more about moving Projects, Tasks, and more.
(Also works with just one, single task).
Hover over any set of tasks. Click on 3 dots next to the task title and then click on 'Duplicate this group'.
This will create a clone of the Tasks (clone) which you can rename (if you wish).
You can repeat the exercise for just 1 single task - simply by dragging a single sub task out of an existing cluster of tasks to make it its own single task. Hover over the single task, and you'll see the ability to duplicate as you did with the group of tasks.
Once you have duplicated the group of tasks (cloned), they can be moved.