Virtual Services work on the concept of matching the incoming request (operation and arguments) to the information stored in the Virtual Service Image. Your ability to match specific transactions, to send unique responses, versus using the META or default response will depend on how you have created your service and how the VSI is configured.
The following links should help you get started on understanding how the service matches against incoming responses.
CA Service Virtualization Concepts - DevTest Solutions - 9.5 - CA Technologies Documentation
Match Tolerance - DevTest Solutions - 9.5 - CA Technologies Documentation