I'm using JBoss 4.2.1 GA with JBoss Messaging 1.4.0 CR1. We've got an MDB listening to a queue. I'm seeing that a message in the queue is delivered twice. I checked to see whether there are any exceptions which causes it to redeliver. There are no exceptions.
It happens at random. Is it a JBoss Messaging bug? Or is there a timeout setting or something like that which causes the message redelivery?
Can you upgrade to SP1 and see if the problem still occurs.
CR1 is a candidate release and not meant for production.