title: Prevent pandas concat'ting my dataframes both vertically and horizontally
body: <p>I am trying to concat two dataframes, horizontally. <code>df2</code> contains 2 result variables for every observation in <code>df1</code>.</p>
  <pre><code>df1.shape 
  (242583, 172)
  df2.shape
  (242583, 2)
  </code></pre>
  <p>My code is:</p>
  <pre><code>Fin = pd.concat([df1, df2], axis= 1)
  </code></pre>
  <p>But somehow the result is stacked in 2 dimensions:</p>
  <pre><code>Fin.shape
  (485166, 174)
  </code></pre>
  <p>What am I missing here?</p>