Multiple user sessions not receiving subscription message - spring stomp websocket

I am using Spring stomp websocket framework to send subscription messages to the clients. We are using ActiveMQ as the message broker and is using a stomp javascript client. Spring 4.1.5 and In this architecture, the messages are sent using

simplemessagingTemplate.convertAndSendToUser(user, "/queue/msg", serverMsg, map);

In order to ensure that only the right user receive their message, I am also making use of a QueueSubscriptionInterceptor that implements ChannelInterceptor. The messages are delivered to the destination correctly. The messages are received using the JS client like this.

  stompClient.subscribe('/user/guest/queue/msg', function(greeting){              
                    x = JSON.parse(greeting.body);
                    ...
                    }

So far so good. However, when there are multiple user session, only one session receives the message. For (e.g), if two "guest" users are logged in, I would like all the two "guest" users to receive the message. This doesnt seem to be happening. Looking into the logs, I see that the message seems to be sent..

2015-04-11 14:39:40 DEBUG StompBrokerRelayMessageHandler:738 - Forwarding SEND /queue/msg-user1 session=_system_ application/json;charset=UTF-8 payload={"my message to you...)
2015-04-11 14:39:40 DEBUG StompBrokerRelayMessageHandler:738 - Forwarding SEND /queue/msg-user0 session=_system_ application/json;charset=UTF-8 payload={"my message to you...)

I see only one client receiving the message and not the other. Reading the Spring documentation, I understand that this is the default behaviour. Can someone tell me what I am doing wrong.

Thanks.