VBA workbook_BerforClose iteration

Private Sub Workbook_BeforeClose(Cancel As Boolean)

   Select Case MsgBox("Library Management System" & vbNewLine & vbNewLine & "Save and Close?", vbOKCancel)
   
' Cancel button pressed, so cancel the close

    Case Is = vbCancel
    Cancel = True
    
' OK button pressed, so save the workbook and close

    Case Is = vbOK
    ThisWorkbook.Close SaveChanges:=True
   
'Close Select Case statement

    End Select

End Sub

This code re-enters the Before_Close routine when it executes the ThisWorkbookClose statement so the Msgbox is output again.

Why ? And can this be avoided ?