Zoho Bookings <> CRM integration

Zoho Bookings <> CRM integration

Hello Zoho community!
We are enabling our Zoho Bookings <> CRM integration. 
What is the workflow if the integration detects that the contact already exists in the CRM? Does it create a duplicate record? Overwrite the record? Merge the record?
(in this case, there would already be a contact with that email address in the Contacts module in CRM)
Thank you