If the two Excel workbooks have the same name, you cannot open them at the same time. For this, either close one of them and then open the other or change the name of one of them.

Alternatively, you can create duplicate worksheets within a workbook if you want two spreadsheets to be presented identically. Need to Duplicate Cell Formatting in Excel? Use This Tool ...

The ability to automate tasks in Excel for the web has been a long wait—but it’s finally here, and it was worth the wait.