Hi Jim,
The :2 has nothing to do with a new tab (worksheet) nor new workbook being added. It refers to the Windows collection.
For example, if you open a new workbook in Excel, it is (probably) called Book1. If you then go to the view tab on the ribbon and click on the "new window" button, you will see in your taskbar that you get Book1:1 and Book1:2. The name of the file has not changed - it is still Book1 - but the :1 and :2 are used to distinguish the fact that you are viewing the same file twice through different windows.
So, in your VBA code, you would continue to use just the filename in the workbooks collection, ie.
Code:
Debug.Print Workbooks("NameWkBk.xlsm").Name
99% of the time you're not going to be interested in the windows themselves but, if you needed to distinguish between them for some reason, you would do so in the Windows collection, ie.
Code:
Debug.Print Windows("NameWkBk.xlsm:1").Caption
Debug.Print Windows("NameWkBk.xlsm:2").Caption
Similarly, this will list the name of each open window pertaining to the workbook the code is in:
Code:
Sub foo()
Dim wdw As Window
For Each wdw In ThisWorkbook.Windows
Debug.Print wdw.Caption
Next wdw
End Sub
Hope that helps?