Maybe this will help?
Hyperlink["https://mathematica.stackexchange.com/questions/9280/open-\
two-copies-of-the-same-notebook", \
CreatePalette[
Button["Duplicate Active Notebook",
NotebookPut[
NotebookGet[
InputNotebook[]] /. {Rule[DockedCells, _] :> Sequence[],
Rule[WindowMargins, _] :>
Rule[WindowMargins, {{0, Automatic}, {0, Automatic}}],
Cell[x___] :> Cell[x, Evaluatable -> False]},
Background -> GrayLevel[0.95], Editable -> False,
"ClosingSaveDialog" -> False,
DockedCells ->
With[{sourcenb = InputNotebook[]},
Cell[BoxData[
ToBoxes[Button["Update",
SelectionMove[InputNotebook[], All, Notebook];
NotebookWrite[InputNotebook[],
NotebookGet[sourcenb] /.
Cell[x___] :> Cell[x, Evaluatable -> False]]]]],
"DockedCell", CellContext -> Cell]],
WindowTitle ->
"Duplicate of " <>
AbsoluteOptions[InputNotebook[], WindowTitle][[1, 2]]];
SetSelectedNotebook[InputNotebook[]]], WindowTitle -> "Duplicate"];
Regards,...Jos