title: Error: ngRepeat:dupes Duplicate Key in Repeater (need track by $index)
body: <p><a href="https://plnkr.co/edit/bpFi5WuojpNO2rh5vF3T?p=preview" rel="nofollow">https://plnkr.co/edit/bpFi5WuojpNO2rh5vF3T?p=preview</a></p>
  
  <p>See the README in the Plunker for the following explaination:</p>
  
  <p>I would like the "INJECT NEW" button to create a blank input under
  the one that was clicked, not at the end. </p>
  
  <p>The reason they are getting added at the end is because of :</p>
  
  <pre><code>&lt;div ng-repeat="problem in problems track by $index"&gt;
  </code></pre>
  
  <p>The <code>track by $index</code> is breaking the injection. </p>
  
  <p>If I take out the <code>track by $index</code> then I get the error:
  <a href="https://docs.angularjs.org/error/ngRepeat/dupes?p0=problem%20in%20problems&amp;p1=object:171&amp;p2=" rel="nofollow">https://docs.angularjs.org/error/ngRepeat/dupes?p0=problem%20in%20problems&amp;p1=object:171&amp;p2=</a>{%22key%22:null,%22component%22:null,%22$$hashKey%22:%22object:171%22}</p>
  
  <p>How can I have the inject functionality but not get the error?</p>