Concurrent access for JMS queue issue in webMethods 7.1.2

I am facing some issues in the JMS. I create JMS input and output queues and the corresponding client with the same name.I have also hanged the properties for the output queue to shared mode. Now I created a JMS Trigger which listens to a particular input queue. When it receives the message a rule is trggered through a IS Service to get that message and put that in another output queue. The IS Service is connected to the JMS Broker server through the MessageConnection/JNDI settings configured in the Integration Server admin page.

I have a JMS client which can spawn threads and sends message to the particular Broker url/connection factory/input queue and listens to the output queue. The issue is that when the client spawns a single thread , the message flows the full path and comes to the output queue from where the client receives it.But when the client spawns more than one thread , we get an exception that the Destination is already is use.

Is this a limitation in webMethods 7.1.2 product suite or there is a way to get rid of this issue ?