You can duplicate a form from your Dashboard. Find the form, click the three dots icon (...), and then select "Make a copy" from the mini-menu.
This will create a duplicate form and take you straight into editor mode for the new copy.
This process copies the form within your account. If you would like to copy a form into the account of a different Paperform user, consider sharing it as a template instead (not available during the free trial period).