title: Stop "filterablebeforefilter" from firing twice
body: <p>Is is possible to prevent this event from firing twice? 
  If I type something in one of the two search fields (searchOne / SearchTwo), the event is fired twice...</p>
  
  <pre><code>$(function() {
      $("#searchOne, #searchTwo").on("filterablebeforefilter", function (e) 
     //....
  </code></pre>
  
  <p>HTML</p>
  
  <pre><code>&lt;div id="divOne"&gt;
      &lt;ul id="searchOne"
          data-role="listview"
          data-inset="true"
          data-filter="true"
          data-filter-placeholder="Search 1..."&gt;
      &lt;/ul&gt;
  &lt;/div&gt;
  
  
  &lt;div id="divTwo"&gt;   
      &lt;ul id="searchTwo"
          data-role="listview"
          data-inset="true"
          data-filter="true"
          data-filter-placeholder="Search 2..."&gt;&lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>