There seems to be a problem with the implementation of the getDeliveringMessages() method on QueueImpl class. The key used to store the values in the returned Hashmap is always the same so what it returns is the value for the last loop iteration.
Justin Bertram <jbertram> updated the status of jira HORNETQ-1477 to Resolved
*** This bug has been marked as a duplicate of bug 1221495 ***