title: Merge Duplicates based on column?
body: <p>Here's my situation - </p>
  
  <pre><code>In[9]: df
  Out[9]: 
      fruit  val1  val2
  0  Orange     1     1
  1  orANGE     2     2
  2   apple     3     3
  3   APPLE     4     4
  4   mango     5     5
  5   appLE     6     6
  
  In[10]: type(df)
  Out[10]: pandas.core.frame.DataFrame
  </code></pre>
  
  <p>How do remove case-insensitive duplicates such that resulting <code>fruit</code> will be all lower with <code>val1</code> as sum of each <code>val1</code>s and <code>val2</code> as sum of each<code>val2</code>s</p>
  
  <p>Expected result:</p>
  
  <pre><code>  fruit    val1 val2
  0 orange    3    3
  1 apple     13   13
  2 mango     5    5 
  </code></pre>