Many are not happy with Apple’s move in OS X Lion by replacing the age-old “Save As..” command with the “Duplicate” command. With “Duplicate”, if you want to save the document as another copy, it’s a two step process with “Duplicate” first and then “Save…”.
OS X Mountain Lion brings back the “Save As…” command to ease the pain. You can issue “Save As…” command using the keyboard shortcut Command-Shift-Option-S. Or press the Option key while in the File menu to access the “Save As…” menu item.
Not all document apps support “Save As…” command yet as apps need to be updated for OS X Mountain Lion. TextEdit or Apple’s Pages, Numbers, Keynote are some of the first apps with the “Save As…” command support.