To copy and paste *keys*:
1) Select the frames that you want to copy by click-dragging, or click then click-shift, in the time track,
2) Select the rows for the keys that you want to copy in the left hand list of controllers,
3) Ctl-C to copy the keys, Ctrl-X to cut the keys,
4) Select the first frame of where you want to paste a copy,
5) Ctrl-V to paste.
This doesn't insert new frames, only adds keys. But if you paste frames that would go past the end of the scene you can extend the scene to include them in the dialog like this that appears:
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Paste extends past end of Scene.
Do you want to extend the Scene to make room?
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Yes No Cancel
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