Zendesk inbox linked to Gmail inbox creates duplicate tickets in other ticketing systems

Dear Zendesk Team,

Within our department we have a Zendesk inbox, which is connected to an external (Gmail) inbox. When the email address of our Zendesk inbox is used to communicate with other departments, (when our email address is CC-d, or we reply from our ZD inbox), it creates duplicate tickets in other departments ticketing system. They use Fresh Service. I was wondering if we can do something from our side to avoid this issue.

Thank you for your help in Advance.

Kind regards,
Edina Bacso