Closed Tickets Triggering Across Zendesk Instances

I have two separate Zendesk instances where a ticket is created in both Zendesk instances(completely two different domains). When the ticket is closed in ZendeskA instance, it is somehow closed by the person in ZendeskB instance, even though that person does not have agent access in ZendeskB.

Any insight as to how Zendesk is detecting this would be appreciated. The event log only shows that the person without agent access is closing the ticket.