Chickens, sheep, rabbits, pigs, cows (mushrooms cows), horses (skeleton, zombie, mule, donkey), iron golem (snow golem), creeper, enderman, blaze, ghast, slime, magma cube (and other ) duplicate your items and xp before dying with potions pitches.
BUG: for the bug to happen, one needs a potion of poison level II, a potion of healing level II, and a potion of level II damage. Choose one of the mobs that I have listed where the bug occurs, and throw the poison potion in it, then immediately wait until the mob suffer the damage of the potion, then throw the potion of healing and damage potion. If you look good, you'll see that the mob will drop your items, XP and the sound and when dead, but will also see that the mob did not die. Then kill the mob and it will drop the items, XP and sound when and killed.

Warning: the bug happens on survival and creative way.