i see this all the time in abyssea. from what i noticed. you are killing mobs that linked, and while finishing off the few mobs or NM or w/e linked.. the original had repopped and the pets still recognize them as a target.. much like when you attack a worm that dives... when it repops the pet already knows to attack it. its only bc of abyssea's rapid respawn rates that i think we see it happening now. i assume the glitch was always there.