title: Python / Pandas - drop_duplicates ValueError
body: <p>I have a very large dataframe. When I run: <code>df=df.drop_duplicates()</code> I get the following error:</p>
  
  <pre><code>ValueError: Buffer has wrong number of dimensions (expected 1, got 2)
  </code></pre>
  
  <p>If I run a <code>df.loc[:10].drop_duplicates()</code> it already bugs</p>
  
  <p>Does anyone know what can cause that?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>The dataframe looks like this:</p>
  
  <pre><code>                                                  Razao_social  Razao_social  \
  business_id                                                                    
  
  17                                             MULTIGRAIN S.A.     Sao Paulo   
  17                                             MULTIGRAIN S.A.     Sao Paulo   
  17                                             MULTIGRAIN S.A.     Sao Paulo   
  17                                             MULTIGRAIN S.A.     Sao Paulo   
  17                                             MULTIGRAIN S.A.     Sao Paulo   
  17                                             MULTIGRAIN S.A.     Sao Paulo   
  38           BRASILAGRO - COMPANHIA BRASILEIRA DE PROPRIEDA...     Sao Paulo   
  38           BRASILAGRO - COMPANHIA BRASILEIRA DE PROPRIEDA...     Sao Paulo   
  71                                    SECURITAS GARANTIAS S.A.     Sao Paulo   
  71                                    SECURITAS GARANTIAS S.A.     Sao Paulo   
  71                                    SECURITAS GARANTIAS S.A.     Sao Paulo   
  71                                    SECURITAS GARANTIAS S.A.     Sao Paulo   
  </code></pre>