The original question was having multiple listeners on a queue. Not only is it possible, it is desirable to have multiple listeners for a queue. There is a difference between listener processes -- any of which can work on a request the same as the rest in parallel in separate threads or even on separate machines -- and having multiple different endpoint consumer processes which are pub/sub.
The whole point of Message Driven Beans used with Queues is to do that. For example, JBoss with an MDB/queue will start up as many MDB (listeners) as it deems necessary to handle the load, and you can have multiple EJB servers pointed to a shared persistent queue. Developers will recognize that doing lots of work in parallel possibly across multiple servers has a huge performance benefit compared with processing only one message at a time.