Howdy Neill,
That’s an interesting question. To answer I think it will help to show you some examples of how a recurring event appears on the front end. Here is a recurring event example. This particular event happens ever 3rd Wednesday of each month. Here is the recurrence that happens on March 18th:
http://wpshindig.com/event/wordpress-santa-cruz-meetup/2015-03-18/
It looks and behaves like any other event, but there is essentially a duplicate of it every third Wednesday of every month as you can see here:
http://wpshindig.com/event/wordpress-santa-cruz-meetup/all/
Does that answer your question? You asked if it creates duplicates. It definitely does. Pre 3.0, especially pre 3.3, it behaved a little bit differently but it still essentially had duplicates.
The only caveat is that there is a setting which limits how long to keep recurring events for. If you want to keep a historical archive you might need to disable this feature. By default it only keeps recurrences for 24 months before it deletes them.
Let me know if that helps paint a clear picture. Cheers!
– Brook