Using a flame 1 bow along with an instant damage II tipped arrow can cause mobs to "die" two or even 3 times. I have tested with various mobs, and all I have tested seem to work. This includes chicken, sheep, cow, zombies, iron golems and creepers. I figure that any other can work in theory, though i haven't tested the ender dragon. I did find creepers to be the easiest.

Steps to replication:
1. Equip a bow enchanted with flame 1, and a damage II arrow.
2. Place down a creeper
3. shoot the creeper once at full power. it should make the death sound and surrender it's experience and gunpowder, but remain standing and on fire.
4. this can be repeated up to three times upon which it dies, or indefinitely if the creeper is healed.

I found that weaker mobs required that the bow be not fully drawn, which was difficult to replicate consistently. for example, sheep need about 3/4 drawn, and chickens require less than half. high health mobs like iron golems need to be weakened first.

Edit: I can confirm that this works in survival as well, albeit an impractical way to obtain extra drops and not likely to be abused.