title: v-for exceeds the number of iterations 3x times
body: <p>I have a simple loop to list videos and a method that accepts each videos and calculates the price.The problem is the method is called 9 times while there are 3 elements in the looop.
  I have an array containing videos named videos</p>
  
  <pre><code>&gt; &lt;li v-bind:key="video.video_id" v-for="video in videos"&gt;{{video.Name}}
  &gt; Price:{{PriceCalc(video)}}&lt;/li&gt;
  </code></pre>
  
  <p>And the method just logs for now </p>
  
  <pre><code>PriceCalc(video){
  console.log(video.video_id);}
  </code></pre>
  
  <p>this is called 9 times while the videos array only has 3 elements</p>