What happens when you use Reincarnate ('Destroy a minion, then return it to life with full Health') on a minion that has the Ancestral Spirit deathrattle (Give a minion "Deathrattle: Resummon this minion.)? Does it result in two copies of that minion? Also how does it effect minions like Harvest Golem that summon a minion on death?
Let's take the example you presented with the Harvest Golem.
If you play Ancestral Spirit on him, and then use Reincarnate, he will die, spawning the 2/1 token, then he will respawn twice, once from Ancestral Spirit and once from Reincarnate. So at then end you'll have, one 2/1 token, and two 2/3 Harvest Golem.
Now just for fun, think about the following combo : play Baron Rivendare then next turn play Leroy, use Ancestral Spirit twice and Reincarnate !!! Enjoy !