title: Trouble merging .xlsx files with pandas
body: <p>I am operating with python 2.7 and I wrote a script that should take the name of two .xlsx files, use pandas to convert them in two dataframe and then concatenate them.
  The two files under consideration have the same rows and different columns.
  Basically, I have these two Excel files:</p>
  
  <p><a href="https://i.stack.imgur.com/3K6YG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3K6YG.png" alt="enter image description here"></a> <a href="https://i.stack.imgur.com/qBQy5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qBQy5.png" alt="enter image description here"></a></p>
  
  <p>I would like to keep the same rows and just unite the columns.
  The code is the following:</p>
  
  <pre><code>import pandas as pd
  
  file1 = 'file1.xlsx'
  file2 = 'file2.xlsx'
  sheet10 = pd.read_excel(file1, sheet_name = 0)
  sheet20 = pd.read_excel(file2, sheet_name = 0)
  
  conc1 = pd.concat([sheet10, sheet20], sort = False)
  output = pd.ExcelWriter('output.xlsx')
  conc1.to_excel(output, 'Sheet 1')
  output.save()
  </code></pre>
  
  <p>Instead of doing what I expected (given the examples I read online), the output becomes something like this:</p>
  
  <p><a href="https://i.stack.imgur.com/uKBXa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uKBXa.png" alt="enter image description here"></a></p>
  
  <p>Does anyone know I could I improve my script?
  Thank you very much.</p>