Hi Dave,
Thanks for taking the time to reach out! Great question–while Event Aggregator will not duplicate the same event imported from the same source, it’s currently not able to identify matching events from different sources. If you want to ensure that duplicate events are not published immediately to your calendar with each import task, you can adjust your plugin settings to have newly-imported events set to draft status. Duplicate events can then be excluded manually, and any remaining events can be published all at once. 🙂
I hope that helps! Thanks again, and let us know if you should have any other questions!