title: Pandas pivot produces "ValueError: Index contains duplicate entries, cannot reshape"
body: <p>I have a pandas table formatted as following:</p>
  
  <pre><code>  anger_metric  metric_name angle_value
  0   71.0991 roll    14.6832
  1   71.0991 yaw     0.7009
  2   71.0991 pitch   22.5075
  3   90.1341 roll    4.8566
  4   90.1341 yaw     6.4458
  5   90.1341 pitch   -10.1930
  </code></pre>
  
  <p>I need to create a view of this that pivots it to sth like this:</p>
  
  <pre><code>  anger_metric  roll yaw pitch 
  0   71.0991     14.6832 0.7009 22.5075
  1   90.1341     4.8566  6.4458 -10.1930
  </code></pre>
  
  <p>Here is my code:</p>
  
  <pre><code>df2= results.pivot(index='anger_metric', columns='metric_name', values='angle_value')
  # results is the pnadas table/list
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>ValueError: Index contains duplicate entries, cannot reshape
  </code></pre>
  
  <p>How to handle this?</p>