Good afternoon Sarah and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
I would love to help you with this topic.
Actually, this is not a built-in functionality of the Events Calendar.
However, the good news is that you can use pretty much any third-party plugin that supports Custom Post types duplication, including: https://wordpress.org/plugins/duplicate-tec-event/
Let me know if that helps.
Have a great day!
Geoff B.