Check Duplicate data and remove it using LINQ Query in C#

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 html

<div>
<asp:GridView ID="GridView1" runat="server">
</asp:GridView>
<br />
<asp:GridView ID="GridView2" runat="server">
</asp:GridView>
</div>

.cs

 DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[4]{ new DataColumn("ID", typeof(int)),new DataColumn("name", typeof(string )),new DataColumn("desc", typeof(string)),new DataColumn("rupees", typeof(int))});
        dt.Rows.Add(1, "Test1", "Test", 1000);
        dt.Rows.Add(2, "Test2", "Test", 1000);
        dt.Rows.Add(3, "Test3", "Test", 1000);
        dt.Rows.Add(1, "Test1", "Test", 1000);
        dt.Rows.Add(2, "Test2", "Test", 1000);
        GridView1.DataSource = dt;
        GridView1.DataBind();

       DataTable newTable = dt.AsEnumerable().GroupBy(row => row.Field<int>("ID")).Select(g =>
        {
        DataRow first = g.First();
        if (g.Count() > 1)
        {
            int sum = g.Sum(r => r.Field<int>("rupees"));
            first.SetField("rupees", sum);
        }
        return first;
    })
    .CopyToDataTable();
        GridView2.DataSource = newTable;
        GridView2.DataBind();