how do i set the multiple datasource to single dropdownlist?

```
 DrpPosition.ClearSelection();
        DrpPosition.DataSource = AdvertizeManager.GetList("", "", "", "");
        DrpPosition.DataTextField = "PNAME";
        DrpPosition.DataValueField = "ADID";
        DrpPosition.DataBind();
        DrpPosition.DataSource = CategoryManager.GetList("", "", "", "");
        DrpPosition.DataTextField = "NAME";
        DrpPosition.DataValueField = "CATID";
        DrpPosition.DataBind();

```