While trying to figure out how to make the pet move correctly (the pathfinding is horrid, imho) I accidently backed up in a corner with two slimes boxing me in (the damn pet wouldn't intercept). However, as they did so, my pet wyrmling decided to move to the same square as one of the slimes, glitching both the slime and the wyrmling. Neither would move nor attack. To fix it I decided to summon a new wyrmling. But lo! The old one didn't die! The new wyrmling killed the slime, freeing the previous wyrmling, at which point I suddenly had two wyrmlings (at near full health, too!)! Just thought you would like to know that this can happen (also please please please work on the pathfinding in general) Edit: http://imgur.com/xs3W6
Joy, just tested summoning a new one. Guess what. (Yes, yes, my current pet number is greater than 2 now)
Not only pathfinding, but, combat... if my pet's getting hit, he should hit back, instead of trying to get to another enemy that he can't access (Behind other enemies, so he keeps skipping turn, wanting to get to one, while getting hit by others) And, I get two pets at once quite often too.
Decided to go on a little bug hunting spree. It seems that the summoning fails to detect that you have a pet if you (a) Glitch the pet into another entity, which seems to completely haywire the detection until number of pets are reduced to zero again. (b) Step on a teleport dish or otherwise put great distance between you and your pet removes the pet from detection from the summoning spell. If you get a new pet and return to the old, they're both follow and help you. Summoning a new pet kills the one you last summoned. Can be repeated.
(c) Let the pet get out of your sight radius then summon another one. (d) Quit and Save, then summon another one. It's entirely possible to have 20 or 30 pets out at once. But pet AI really is terrible. As a previous poster mentioned, they seem to become fixated on killing certain enemies even if they physically cannot reach those enemies and other enemies in melee range are beating their face in.