Take a look at this help page on ActiveMQ. It explains how durable subscriptions work against a topic. In particular this:
JMS specification dictates that the identification of S is done by a combination of the clientID and the durable subscriber name. This is so that the JMS connection S uses can have many different durable subscriptions on different topics or on the same topic with different selectors - yet the JMS provider can know which message for which subscription to keep around for it.
You need to use different IDs for different consumers.