merge gridview columns in asp.net

public partial class _Default : System.Web.UI.Page
    {
        private bool _alternate = false;

        protected void Page_Load(object sender, EventArgs e)
        {
            DataSet ds = new DataSet();
            ds.Tables.Add(new DataTable("Employee"));
            ds.Tables[0].Columns.Add("Id");
            ds.Tables[0].Columns.Add("Name");
            ds.Tables[0].Rows.Add("1", "Name1");
            ds.Tables[0].Rows.Add("1", "Name2");
            ds.Tables[0].Rows.Add("2", "Name3");
            ds.Tables[0].Rows.Add("2", "Name4");

            GridView1.DataSource = ds;
            GridView1.DataMember = "Employee";
            GridView1.DataBind();
        }

        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            GridView1.RowDataBound += new GridViewRowEventHandler(GridView1_RowDataBound);
        }

        void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (_alternate)
            {
                e.Row.Cells[0].ColumnSpan = 2;
                e.Row.Cells.RemoveAt(1);
            }

            _alternate = !_alternate;
        }
    }