If a customer submits multiple enquiries regarding the same order number/issue, we recommend responding to the customer to advise which ticket will be their main ticket for this enquiry. Please mark the duplicate ticket as solved.
Example response to customer:
Hello, we can see that you have already raised a ticket regarding this, on Ticket ID ___. In order to provide efficient service, we will respond to your queries on your main ticket. This duplicate ticket will be closed.