What happens if you use vba to open a closed workbook that's already open?

I'm using this code to read from a closed workbook.

Sub Test()

Dim wb As Workbook
Dim AWS

Application.ScreenUpdating = False

Set AWS = ActiveSheet

Set wb = Workbooks.Open("E:\Archive\Test.xlsx", True, True)

AWS.Range("A1") = wb.Sheets(1).Range("A1")

wb.Close False

Application.ScreenUpdating = True

End Sub

Please can someone tell me what would happen if the workbook was already open? Could this cause any problems?


What's the best way of detecting if a workbook is already open?

Regards,

Rowan