Highlight GridView rows with same (matching) data (values) in ASP.Net

Hi zzz,

I have created one sample that full-fill your requirement.

HTML

<div>
    <asp:GridView ID="GridView1" HeaderStyle-BackColor="#3AC0F2" HeaderStyle-ForeColor="White"
        runat="server" AutoGenerateColumns="false" OnRowDataBound="DataBound">
        <Columns>
            <asp:BoundField DataField="Id" HeaderText="Id" ItemStyle-Width="30" />
            <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
            <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
        </Columns>
    </asp:GridView>
</div>

Code

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[3] { 
                        new DataColumn("Id", typeof(int)),
                        new DataColumn("Name", typeof(string)),
                        new DataColumn("Country",typeof(string)) });
        dt.Rows.Add(1, "John Hammond", "United States");
        dt.Rows.Add(2, "Mudassar Khan", "India");
        dt.Rows.Add(3, "John Hammond", "United States");
        dt.Rows.Add(4, "Mudassar", "India");
        dt.Rows.Add(5, "Mudassar Khan", "India");
        dt.Rows.Add(6, "Suzanne Mathews", "France");
        dt.Rows.Add(7, "Suzanne", "France");
        dt.Rows.Add(8, "Suzanne", "France");
        dt.Rows.Add(9, "Mudassar Khan", "India");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}
protected void DataBound(object sender, GridViewRowEventArgs e)
{
    for (int current = 0; current < GridView1.Rows.Count; current++)
    {
        for (int other = current + 1; other < GridView1.Rows.Count; other++)
        {
            GridViewRow compareRow = GridView1.Rows[current];
            GridViewRow row = GridView1.Rows[other];
            if (((compareRow.Cells[1].Text) == (row.Cells[1].Text)) && ((compareRow.Cells[2].Text) == (row.Cells[2].Text)))
            {
                compareRow.BackColor = Color.Green;
                row.BackColor = Color.Green;
            }
        }
    }
}

Screenshot