Key copier is a 3ds Max script from Chuggnut that adds Ctrl+C and Ctrl+V copy-and-paste for keys inside the track view. It brings a familiar keyboard shortcut pattern to key handling in the track view interface.
The script uses Chugg_globals, which is documented in the accompanying help text. This dependency is noted directly by the developer, so users should consult the help file when setting it up. It is listed for Max 4.x.
Key copier is available through ScriptSpot, where it currently sits at popularity rank 3150. The developer's own page at chuggnut.com is the primary reference for the script and its supporting documentation.