I was playing BG2 this morning with my Kensai12/thief29. I have Simulacrum in her quick slot and vhailors helm equiped. i cast the simulacrum and then made the simulacrum cast another simulacrum so i had 3 of me running around though the copied copy didnt have any items on her(that i could see). she still had all her ablities, though if u tried changing in to the slayer with either copy the real you would change instead.
back to the 2nd simulacrum after more testing i tried backstabbing I attacked edwin. he took about 28 damage when i backstabbed him.