Hey Kim,
Thanks for reaching out. There are unfortunately no official methods for cloning an event. 🙁 And so at this time, yes, a third-party solution would probably be required.
While we don’t officially recommend any specific third-party solution for this, and thus cannot guarantee they’ll work as advertised, several customers have reported success with the following free plugin on WordPress.org → https://wordpress.org/plugins/duplicate-tec-event/
I hope that helps!
George