can i duplicate a form

Yes, you can clone a form in your own account:

https://www.jotform.com/help/27-How-to-clone-an-existing-form-from-your-account

Or you can clone a form to/from another account with its URL:

https://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL