To duplicate a project, open the project and click Project Details.
Then scroll to the bottom and click 'Duplicate'.
When you duplicate a project, everything about the project will be presented as a brand new project. You can then change the Client associated with it, therefore using it as a template for a new project.
As always, feel free to ping us on the support chat and let us know if you have any questions!
Follow this link for a video on duplicating and deactivating projects: Duplicate and Deactivate