Disallowing login to user already logged in

Hello,

i've got a problem with my ejabberd config. Actually i wanted to use the anonymous login for my client because users should be able to just loggin without doing anything. But that doesnt work with my JavaScript Xmpp Library "Strophe JS". So i wanted to prepare an algorythm that trys to login in to several users and stays on the one that is still free.
My Problem now is that when a client(1) is connecting to a user that is already logged in from client(2), the client (2), that is already working, is kicked out.
Is it possible to configure the server different, so that he is disallowing the new user to log in to that account already in use?

Much thanks for help