Found this out earlier tonight on my server and it appears to be kind of an underground bug atm.
Bot casters when they summon a pet can get rid of that pet with the cmd
#bot pet remove
when done and the pet is targeted this gets rid of the pet....it also gives the player experience that is at least substantial.
i got rid of this by removing pet summoning spells from my bot lineups but i would really like to see an actual fix for this. if anyone knows of a way to fix please let me know