Cloning a template very easy to do, and is essentially copying and pasting the underlying code behind a template.
Steps:
Go to the folder where the template was originally created (Home/Team folder)
In the Templates tab, select the checkbox of the relevant template
Click Edit Template
In the bottom left, click Show Raw Code
Select all of the text, right click and click Copy
It is important to copy all of the text, and do not change any of it. If you do, it wont work
Exit the template editor
Go back to the templates section and click Add Template
You may need to un-select the original template to reveal this button
Select Build Your Own and enter the details of your new template
In the template editor, click Show Raw Code
Remove any exisiting code & paste in your code
Click Hide Raw Code to see all of the fields
Click Save when you're done
Note: Team members are not able to add or edit templates, and hence will not be able to clone templates