new version of Extension plugin is here 0.10.1 with fix for Google Sync and duplication of events. Please update if you encounter this issue.
I’m having the issue with duplication of events.
If I setup the advanced calendar sync option then I get duplication. If I just leave it as my primary calendar then I get new events created but no duplications. In either case deleting an event from either google side or EA side will not sync so it is left sitting on one or the other.