title: drop duplicates pandas dataframe
body: <p>I am getting an error message when using drop_duplicates to drop duplicate columns from my dataframe.</p>
  
  <pre><code>ValueError: Buffer has wrong number of dimensions (expected 1, got 2)
  </code></pre>
  
  <p>Below is a min example (notice that I don't have duplicate column names here, since that column won't be added then, so I var1 would be called var0 in my actual dataframe)</p>
  
  <pre><code>dict1 = [{'var0': 0, 'var1': 0, 'var2': 2},
           {'var0': 0, 'var1': 0, 'var2': 4},
           {'var0': 0, 'var1': 0, 'var2': 8},
           {'var0':0, 'var1': 0, 'var2': 12},]
  df = pd.DataFrame(dict1, index=['s1', 's2','s1','s2'])
  df.T.drop_duplicates().T
  </code></pre>