Typically, when you hit Command-N while you’re in the Finder, you’ll get a window for the folder you have set in the Finder’s Preferences dialogue. But what if you want to open two copies of the same folder on your Mac, to move stuff around in sub-folders when in icon view, for example? If you want to open two copies of the same folder on your Mac at the same time, simply do the following.
Open a Finder window, first of all, and then click on the View menu, choosing Show Path Bar. Now you’ll be able to see the current path to the folder you’re viewing at the bottom of the Finder window.
Now the trick – with any other folder in the Finder, you can Command-double click to get a new window to that folder. With the Path Bar showing, you can Command-double-click the same folder you’re using in the Path Bar, getting a new window to the same window you’re viewing. Get it?
Now you’ll be able to open two copies of the same window in the Finder, letting you move stuff to and fro with ease when in icon view.
Via: Macworld Hints