title: Adding data to an existing Excel file with python
body: <p>I need to add some data to an existing Excel file. My script only adds data to a new sheet. When I try to write into an existing sheet (e.g. <code>template</code>) of my existing file, it creates two different sheets (e.g. <code>template</code> and <code>template 1</code>). How can I prevent this?</p>
  
  <pre><code>precios_read = pd.read_excel('Precios_{}.xls'.format(auth2), sheet_name='Precios')
  
  book = load_workbook('Template_sugerencia.xlsx')
  writer = pd.ExcelWriter('Template_sugerencia.xlsx', engine='openpyxl')
  writer.book = writer
  precios_read.to_excel(writer, sheet_name='template', startcol=12, startrow=5, index=False, merge_cells = True)
  Recom.to_excel(writer, sheet_name='template', startcol=0, startrow=5, index=False, merge_cells = True)
  writer.save()
  </code></pre>