Google Calendar booking added to DB again and again...

Hello, I just figured out that the appointments I make directly from Google Calendar are added to my Appointment+ backend as "Booked from Google Calendar", nothing bad since here...
But I discovered that the appointments are added hundreds of times !!!
I guess this is a huge loss of energy to the little plugin.
Here is a screenshot of this disaster; how can I fix this ?
PS: I have <10 different appointment on my google calendar.