This is a very common question, so hopefully this post can be a good reference. There is a new hotkey command called DuplicateWindow which lets you 'clone' an existing Montage, Time/Sales, or Chart window. All settings like hotkey buttons, colors, fonts, etc. will be copied over.
How to:
-Go to menu Setup > Hot key
-Add New Item
-Enter a Name and Hot Key. In the Script Field, enter DuplicateWindow
-Press Commit
Now you can simply select the window you wish to duplicate, then press the hotkey (CTRL+D in the above example). And voila, attack of the clones!