Is it possible to duplicate an existing form to save time?

Yes, it is possible to clone or copy a form.

To clone a form using its link, you can follow this guide: http://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL 

If the form is existing in your account, you can clone it directly there by following this one: http://www.jotform.com/help/27-How-to-clone-an-existing-form-from-your-account 

Do let us know if you need more information on this.