You have (unintentionally?) turned on VoiceOver - the menu items are not duplicates like you have listed (the second option will be lacking the ellipsis (which means that selecting it will cause the action to occur immediately without any prior warnings - it is the equivalent of holding option down while making the same menu selections when VoiceOver is off).
To turn off VoiceOver (assuming you don't actually use it), go to System Preferences>Universal Access>Seeing.
The default shortcut for activating it is command-F5 which is also used in Quark for something so some people can activate VoiceOver by mistake. There may be other apps that use the same shortcut or it could just have been a mistype that switched it on.
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