I don't know if we'll ever know the source of the trackball version for certain.
This much I know - info on KLOV is VERY OFTEN wrong (if necessary, I can dig up some examples), and lots of other sites copy info from KLOV. So just because KLOV says it was a later version, means absolutely nothing.
To me, the fact that the Trackball artwork has no brand name or logo on it, and looks absolutely NOTHING like the original sideart, marquee art, or CP art, strongly suggests that it is an aftermarket add-on. Also, upgrades and conversion kits were pretty common as a way to bring interest back to an old game (or cabinet), so something like a trackball add-on for a game where some people couldn't do well with buttons seems like a sellable item. Obviously, I can't prove this is how it happened, but it just seems like the most likely scenario.
Wade