Here is a possible solution.
Your Main Project has a Section called “Template - Tasks - Don’t Delete” in here you have all of the Master Task with the relevant SubTasks.
You then have what ever other relevant Sections etc that you need. Example below;
These Tasks are then associated with another Project which will act as your Task Template Project, the task will look something like this.
Then when you need to duplicate the tasks you copy the “Template Project” making sure that you select “Other Projects” You will then get this result in your Main project.
Now you can move those tasks into the right Section. You can then Delete the “Copy of Project” and that project will be removed leaving the tasks in the correct project and section as per below;
Hope this helps or maybe someone else has another solution…