You can clone keys by holding down
while dragging. New keys are added to the existing keys in the same track.
To move a selection of keys in Curve Editor:
Only keys in highlighted tracks appear in the Key window.
By default, the
Move Keys button is highlighted.
and drag the highlighted keys to add copies at the new location. If you drag a highlighted key on top of another key, the moved key replaces the other one.
To move a selection of keys in Dope Sheet:
+click to highlight non-contiguous keys.
to lock the key selection. Then you don't have to drag over the selected key, but anywhere in the viewport. This is useful when you have a complex selection set of keys. The Move Keys tools are available from a flyout on the Keys toolbar in both Track View modes, and also on the Key Controls toolbar in Track View - Curve Editor. The default tool, Move Keys, lets you move keys in any direction in Curve Editor. In Dope Sheet, all three tools allow horizontal (timing) movement only.
Moves keys in both horizontal and vertical axes, to change both timing and values.
Constrains movement to the horizontal axis, to change timing.
Constrains movement to the vertical axis, to change values.