Navigate to the Events section of your Organization and hover over the Event you want to duplicate. Click on the blue copy icon to get started.
This will prompt you to edit some information for the new Event. You will have to add a new start date, as well as choose whether or not you would like to copy over Staff and their assigned Shifts. When you're done, click the 'Copy Event' button in the bottom-right. Please note, when copying an Event, the new Event will automatically be set to 'Hidden' and will not be Live.
And it's that easy! Now you can see your newly copied Event and you can customize it as you see fit.