This was a another thread which has been marked resolved - however the solution was not posted within the forum. I am having the same issue... please help!
Every time I do a sync, the event data is imported multiple times. Here a brief description:
events are imported twice, once for author "admin" and once for post_author = 0
every further sync:
will do the same, so after 2 syncs each event is listed 4 times in the backend
3. on the website each event is displayed, correctly, only once