Open 2 Excel Files in separate windows

WARNING: Changing your registry can be dangerous to the health of your computer. Do so at your own risk.

This change makes it so when you click an Excel file it will ALWAYS open in a new window (a different instance of Excel)

 

.XLSX

1. I highly recommend you back up your registry before making any changes.
2. Open regedit.exe
3. Navigate to HKEY_CLASSES_ROOT/Excel.Sheet.12/shell/Open/command
4. Open (Double-click) the key called (Default)
5. Change the value from
         "C:\Program Files (x86)\Microsoft Office\Office12\EXCEL.EXE" /e
   to "C:\Program Files (x86)\Microsoft Office\Office12\EXCEL.EXE" /e “%1”
6. Click the OK button
7. Below the (Default) key you will see a key with the name command.
   Right click it and select Rename.
   Change the name to something else (it doesn’t matter what)
8. Your screen should now look something like the following (I appended bv to the command key, but you should probably use something different)
   
   
   
9. Navigate to HKEY_CLASSES_ROOT/Excel.Sheet.12/shell/Open/ddeexec
   Right click it and select Rename.
   Change the name to something else (it doesn’t matter what)
10. Your screen should now look something like the following:
    
    
    
11. You have now successfully made it so that when you open an existing Excel file (that has the extension .xlsx) it will open in a new window. This allows you to easily compare or view two Excel file at the same time. This is particular helpful if you have two monitors. You can also ways revert back if you decide you don’t like the change by undoing the changes made here, that is why we renamed instead of deleted the keys.

.XLS

You can follow the same instructions for .XLS except you will want to amend the instruction so that where ever you see Excel.Sheet.12, replace it with Excel.Sheet.8.

BTW, I found this tip here.