Hi,
is the 2nd window called personal.xlsb? If so click on this window and to get rid of it is to go to the View tab and click Hide. This file is where your personal macros may be stored. I had it opening for a while and it annoyed me so I have hidden mine from view.
if its not called personal.xlsb then I found the instructions below on
answers.microsoft.com (this is a link to the post/page) - In this example option C cured the issues as the user had recently installed MySQL and this set an option to open a blank Excel file each time via a COM add in!!
Please make a note of any options you change as if it doesn't cure the issue then I always think its best to put the settings back
Please try the followings to see the result:
a.Disable preview pane in File Explorer (open File Explorer, click View tab and make sure Preview Pane is not enabled).
b.Navigate to C:\Users\<username>\AppData\Roaming\Microsoft\Excel\XLSTART check if there is any file and move it to other location.
c.Open Excel and go to File tab->Options->Add-ins, Set "Manage" to "COM Add-ins" and click Go, Write down which add-ins are selected, uncheck them all, choose OK.