List boxes based on same dataset.

Question

I have two list boxes both based on the same dataset (have the same datasource, displaymember and valuemember). Changing the value in one of them (listBox1_SelectedIndexChanged), changes the value in the second list box (listBox2_SelectedIndexChanged), to the same value. I don't understand why the two different controls are behaving as one entity. Does this have something to do with my basing both of them off the same dataset? I don't see why I should be creating a different dataset when both the listboxes are required to display the same set of values from the database table. Thanks for any help.