How to take value from one cell and add to list over multiple excel files

Question

I'm trying to select the same cell from multiple excel files and add them to a list, but I keep getting double of the same number. How do I solve this? I'm using xlrd, os, and numpy libraries to do this.

for root, dirs, files in os.walk("/Users/Isaac/Experiment"):
   xlsfiles = [_ for _ in files if _.endswith('xlsx')]
   my_matrix = []
   my_matrix_2 = []
   for xlsfile in xlsfiles:
      workbook = xlrd.open_workbook(os.path.join(root,xlsfile))
      worksheet = workbook.sheet_by_index(0)
      for col in range(worksheet.ncols):
          my_matrix_2.append(worksheet.cell_value(4,1))
   print my_matrix_2

What I get as as a result is [4.0, 4.0, 40.0, 40.0, 44.0, 44.0, 48.0, 48.0, 52.0, 52.0, 56.0, 56.0, 60.0, 60.0, 64.0, 64.0, 68.0, 68.0, 72.0, 72.0, 76.0, 76.0, 8.0, 8.0, 80.0, 80.0, 84.0, 84.0, 88.0, 88.0, 92.0, 92.0, 96.0, 96.0, 100.0, 100.0, 12.0, 12.0, 16.0, 16.0, 20.0, 20.0, 24.0, 24.0, 28.0, 28.0, 32.0, 32.0, 36.0, 36.0]