title: Duplication localStorage data using backbone.js + backbone.localStorage.js
body: <p>I'm using backbone + backbone.localStorage to persist my data, and I get a wrong behavior:</p>
  
  <p>I've got a model settings with one attribute called user</p>
  
  <pre class="lang-js prettyprint-override"><code>Settings = Backbone.Model.extend({
      localStorage : new Backbone.LocalStorage('settingsStore')
  });
  var settings = new Settings();
  settings.set({user: 'USERNAME'});
  settings.save();
  </code></pre>
  
  <p>After this code if I output the settings.attributes data in weinre I get the following:</p>
  
  <pre class="lang-js prettyprint-override"><code>  settings.attributes  
     Object  
     id: "3ac78cfb-ad60-1ab8-8391-f058ae9bfcfb"  
     user: "USERNAME"  
     __proto__: Object
  </code></pre>
  
  <p>Then I save the model to the localStorage, clear, and fetch it again:
  </p>
  
  <pre><code>settings.save();
  settings.clear();
  settings.fetch();
  </code></pre>
  
  <p>And the problem is that if I output the settings.attributes, now this attributes are stored inside a nested object:</p>
  
  <pre class="lang-js prettyprint-override"><code>   settings.attributes  
     Object  
     0: Object  
         id: "3ac78cfb-ad60-1ab8-8391-f058ae9bfcfb"  
         user: "USERNAME"  
         __proto__: Object  
     __proto__: Object
  </code></pre>
  
  <p>And the problem is when I set the user name again in order to modify, a new attribute is added like this:</p>
  
  <pre class="lang-js prettyprint-override"><code>   settings.attributes  
     Object  
     0: Object  
     id: "3ac78cfb-ad60-1ab8-8391-f058ae9bfcfb"  
     user: "USERNAME"  
     __proto__: Object  
     user: "NEWUSER"  
     __proto__: Object 
  </code></pre>
  
  <p>And if I save this model, and fetch it again I get 2 new objects on the attributes... and it keeps growing each time.</p>