Private WithEvents App As Application

Private Sub App_WorkbookBeforeSave(ByVal Wb As Workbook, ByVal SaveAsUI As Boolean, Cancel As Boolean)
     If InStr(1, Wb.Name, "Copy of ") = 1 Then
         Application.EnableEvents = False
         Cancel = True
         Wb.SaveAs Replace(Wb.FullName, "Copy of ", "")
         Application.EnableEvents = True
     End If
End Sub

Private Sub Workbook_Open()
     Set App = Application
End Sub

If InStr(1, Wb.Name, "Copy of ") = 1 Then

Application.EnableEvents = False
Cancel = True
Wb.SaveAs Replace(Wb.FullName, "Copy of ", "")
Application.EnableEvents = True

Private WithEvents App As Application

Private Sub Workbook_Open()

Set App = Application
    
End Sub

Private Sub App_WorkbookBeforeSave(ByVal wb As Workbook, ByVal SaveAsUI As Boolean, Cancel As Boolean)

If SaveAsUI Then

    Cancel = True
    With App.FileDialog(msoFileDialogSaveAs)
        .InitialFileName = wb.FullName
         
        p = InStrRev(wb.FullName, ".")
        If p > 0 Then
            ext = "*" + Mid(wb.FullName, p)
            For i = 1 To .Filters.Count
                If .Filters(i).Extensions = ext Then
                   .FilterIndex = i: Exit For
                End If
            Next
            If (ext = "*.mht" Or ext = "*.mhtml") Then .FilterIndex = 7
            If (ext = "*.htm" Or ext = "*.html") Then .FilterIndex = 8
        End If
         
        If .Show = -1 Then
            If (.FilterIndex = 2 Or .FilterIndex = 10) Then
            wb.SaveAs .SelectedItems(1), FileFormat:=xlOpenXMLWorkbookMacroEnabled
            Else
            wb.SaveAs .SelectedItems(1)
            End If
        End If
        
    End With

End If

End Sub