Win Forms, C# code behind, simple DropDownList control

When I select an entry on the DDL, my event code runs twice.
Why?
How can I get it to quit stuttering?

public void ddlSources_SelectedIndexChanged(object sender, System.EventArgs e)
{
  // code runs twice
}

Larry A. Halliday

you must check this
page load()
if(this.Page.IsPostBack==false)
{
//bind ddl with source here
}

please check the syntax

ashfaq