Sometimes an existing event serves as a useful template on which you might base other very similar events. There are actually lots of duplicate post plugins out there (including at least one that is The Events Calendar-specific) however Event Rocket also now adds this capability.
Simply view the list of events (in the admin environment) and look out for the duplicate action:
Clicking duplicate will bring up a modal window where you can optionally specify a custom title and set the date on which the duplicate event should take place. These can be left blank if you prefer to quickly make the duplicate and edit it later in the actual event editor.