Really, for NWN purposes, that is one and the same. Simply changing its animation cycle name changes it to a new animation. So what I mean is, you can change the name of an animation cycle, and then go back and add the original name again via nwmax. This puts your "new" animation out of reach of the engine (without modifications), but lets you swap it back in later, by simply changing the text of the model file.
I don't know of a full rundown of the integer values of each animation cycle, but I do know that the animation cycles can only be called from script by integer, not by name string, which is annoying beyond reason. The order of the animations in the MDL file makes no difference, so I know that only can mean that the text names of the animation cycles are built into the game executable, and then called by integer index to the hardcoded table. What I'd like to see is a NWNCX mod that lets you call animations by name string, or otherwise lets you modify that table as an external 2da. By name would allow you unlimited animations. By 2da index would at least give you a ton more. The other benefit to by-name calling is that it would be universal, and no hak would be needed except the additional animation cycles MDL file(s).
I've found that you can make certain unit models more versatile by supplying both character and creature animations. Depending on how the integer calls line up, you might be able to get additional attack or emote animations built into a character by doing that.
Here's a very limited list of the known integer indices, but does not include actual text cycle name.
http://www.nwnlexico...title=Animation
Because creatures and playable characters use different cycle names for their similar combat animations, I wonder if the animation indices line up perfectly name-to-name, or if there is also some internal negotiator which says, "ok, I am model type creature, play ca1SlashL, instead of nwSlashL" (creature attack as opposed to no-weapon attack)