Path of Exile – What Maps Have Multiple Organ Droppers?

From the mechanics thread:

Increased Item Rarity Increased Item Rarity % modifiers increase the chances of an item being magic, rare, or unique. For example with a total of +100% increased item rarity, you'd get twice as many magic items, twice as many rares and twice as many uniques from normal enemies. This modifier has no effect on the number or type of currency items, scrolls, or gems that drop. When in a party, only the modifier from the player who lands the killing blow on an enemy is counted. If one of your minions gets a kill, the minion's IIR is added to yours and the total is used.

Magic, rare, and unique monsters have an Increased item rarity modifier for drops.

Not really. I don't think there is any unique that's as cheap as 5 chances. Cheapest uniques are the ones that aren't very useful and with low rolls, and even those can be sold for at least 2 alchs (1 alch = 4 chances).

That's based on Hardcore League economy at least, i don't play default league so i don't know are their rates any different.