The Great Divide

This one is quite simple. Upon finding the town of Split, you meet several people who have twins. It turns out that a mage of some sort decided that everyone has a Demented side, and a Manic side. In order to bring out the best of each, they cast a spell that doubled everyone in town, thus "Splitting" them into two. Anyway, one of the townspeople will reward you for killing all of the "Mania" versions of the the doubles. Be careful, if you kill any Dementia doubles you won't get a reward of any kind. Also, be aware that if the dementia's catch you in your killing spree, you will rack up a hefty fine and will be confronted as soon as you enter the main city.