Hi,
Jamie is correct about the version that you are currently running. The current production version of Service Desk is 7.7.3 and unless there are specific technical reasons which may be preventing you from upgrading, it would be a highly recommended step to take, not just because of the ongoing sustainment, but also as there are a significant set of new features and functions available through the subsequent releases. As far as creation of the ticket is concerned, there are only three ways that a new ticket can be created... via an analyst logging it, email or self service. When you say duplicate ticket creation, what do you actually mean? Is this a user asking for the same thing to be logged more than once or is the something that appears to be happening from Service Desk without any external action?
Andy