title: Replace duplicated values with a blank string
body: <p>I have a pandas dataframe </p>
  
  <pre><code>df = pd.DataFrame([{'a':'Male','c1':3,'c2':10},{'a':'Male','c1':3, 'c2':30},{'a':'Male','c1':1,'c2':20},{'a':'Female','c1':2,'c2':15},{'a':'Female','c1':2,'c2':100}])
  </code></pre>
  
  <p>I want to print the bellow:</p>
  
  <pre><code>   a      c1   c2
  0  Male   3    10
  1              30
  2  Male   1    20
  3  Female 2    15
  4             100
  </code></pre>
  
  <p>Would you please help me?</p>