Go to the [*Dope Sheet* editor][1], there are several ways to do this:

* Click the icon on the bottom left corner of the 3D view and select *Dope Sheet*

 ![enter image description here][2]

* Click on the dropdown that says *Default* on the *Info bar*, and select *Animation*. (Or press <kbd>Ctrl</kbd><kbd>Left Arrow</kbd> twice)

 ![enter image description here][3]

 This will take you to the [*Animation layout*][4], with a [*3D view*][5], [*Graph editor*][6], and *Dope sheet*.



From the *Dope sheet* or the *Graph editor*, select keyframes, and press <kbd>Shift</kbd><kbd>D</kbd> to duplicate.


  [1]: http://wiki.blender.org/index.php/Doc:2.6/Manual/Animation/Editors/DopeSheet
  [2]: https://i.sstatic.net/tKmrp.png
  [3]: https://i.sstatic.net/Rm17m.png
  [4]: http://wiki.blender.org/index.php/Doc:2.6/Manual/Interface/Screens#Screens
  [5]: http://wiki.blender.org/index.php/Doc:2.6/Manual/3D_interaction/Navigating/3D_View
  [6]: http://wiki.blender.org/index.php/Doc:2.6/Manual/Animation/Editors/Graph