Anyway, Oracle doesn't recommend this; What if the user is already connected? Shutting the listener down won't get him away, you would have to "kill him".
The recommended way is shutting the database down and bringing up in restricted mode.
You should have only one listener.ora with many LISTENER_SOMETHING entries, and to start it you should put
$ lsnrctl start listener_something
Try it.
(Check the port is not in use)