Excel is MDI (Multi Document Interface till Excel 2010. i.e; when you open a new workbook, it will open in the already opened  ApplicationWindow. We can Open multiple Excel Workbooks in the Different Window in different methods:

  1. If the Excel Application or an Excel File is already opened, We must open new Application and Use the Open command from the File Menu to open the file.
  2. If the Excel Application is already opened, we can drag the workbooks and drop in the newly opened Excel Application Window.
  3. We can also change this default behavior from the Excel Options to open new workbook in a new window every time.