Managed Server Listener Ports and Web tiers

We're not what would be called Weblogic experts and mostly self-taught via google and trial and error.  So hopefully the question isn't too dumb. 

In our current Weblogic 11 environment we set up each cluster to have it's own listener port.  So if clusterA had two managed servers, those managed servers would share a listener port.  But clusterB would be a different port, and so on.

We are in the process of building a new Weblogic 12 environment and setting up the clusters and managed servers.  Is there a technical need or advantage to assign different ports for the different clusters/managed servers or is this unnecessary?