Pubnub receiving duplicate messages

I am using PubNub for in-app chat with Backbone and the javascript sdk. If I navigate to another view and return to the chat window, when I publish a message I receive it in duplicate. If I browse away again I receive messages in triplicate and so on.. I think I am subscribing again and again each time I return to the chat page - but I can't get the unsubscribe to work and I can't find any documentation on where else to subscribe from. Is there a check I can use to see if I am already subscribed? My code is: ``` // INIT var channel = 'my_channel'; var pubnub = PUBNUB.init({ subscribe_key : 'demo', publish_key : 'demo' }); function chat(message) { if (message.uid == "xxx") { $("#convo").append('<div class="isaid">' + message.message + '</div><div class="clear clearfix"></div>'); } else { $("#convo").append('<div class="hesaid">' + message.message + '</div><div class="clear clearfix"></div>'); } } pubnub.history({ channel : channel, // USER_ID Channel limit : 30, // Load Last 50 Messages callback : function(msgs) { pubnub.each( msgs[0], chat ); } }); pubnub.subscribe({ channel: 'my_channel', callback: function(data) { chat(data); } }); pubnub.publish({ channel: 'my_channel', message: data }); ```