Why are ticker messages in the MtGox PubNub API repeated?
PubNub MtGox API Ticker Repeat Messages

The Ticker Events are Updates that are streamed directly to you which may or may not represent a price change.  However the ticker updates are typically tied to a trade event which occur on the trade channel.

You can find the trade stream here: 
http://www.pubnub.com/console/?sub=sub-c-50d56e1e-2fd9-11e3-a041-02ee2ddab7fe&amp;pub=demo&amp;channel=dbf1dee9-4f2e-4a08-8cb7-748919a71b21&amp;origin=pubsub.pubnub.com&amp;ssl=true

So in regards to the updates you may receive unchanging value updates.  You may also consider looking at historical values by using the History API: http://www.pubnub.com/how-it-works/storage-and-playback/

Also check out the related Stackoverflow article: https://stackoverflow.com/questions/20547815/convenient-way-to-extract-data-from-the-mtgox-pubnub-json-api/20553315#20553315

or 

https://stackoverflow.com/questions/20495713/are-there-ready-made-java-classes-for-the-mtgox-pubnub-json-api/20500700#20500700