**tested on latest arcemu**
to fix it you put the spellid1 (summon spell) of the pet you want to fix in spellid2 with the trigger 6 charges 0... spellid1 is 483 (learning spell) trigger 0 charges -1.
so in closing
spellid2 = spellid1
spelltrigger_2 = 6
spellcharges_2 = 0
spellid1 = 483
spelltrigger_1 = 0
spellcharges_1 = -1
after this you right click the pet and poof you know the summon spell (added to your collection) and is disappears like on retail *claps*
this also works for mounts... except with some of the mammoths it makes a pet that follows you *shrugs* prolly core handling of the mount summon spell.
**tested on latest arcemu**