Experience Range will be taken into consideration. Lets take this example, lets say you killed off a grunt and a tc. The Grunt is worth 60 and the TC is worth 100 at level 1. If you are playing Solo, you get 160 experience to your one hero. Your second hero will divide it by 2. The first hero gets 80, and the second hero gets a small bonus to the 80.
If there are say 5 heroes in the area in a team game. Then its 160/5, plus any bonuses if they got thier second heroes. So basically, it is divided by the number of heroes within a certian area of the kill.