gcal integration duplicate appointments

I've updated the gcal credentials and have two way syncing setup. When I book appointments on the site they appear correctly on the back and and on the calendar. However if I make an appointment from the Google Calendar the appointment ends up with duplicates (it looks like there is a new one processed every time the plugin "updates"). There's now 20 appointments for the ones I put in the Google calendar. I'm assuming this isn't normal?