The variable name @orders has already been declared. Variable names must be unique within a query batch or stored procedure.

 protected void send_Click(object sender, ImageClickEventArgs e)
    {
     //   DataAcess data = new DataAcess();
        cm.Connection = con;
        cmd.Connection = con;
        con.Open();
           
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            String items = GridView1.Rows[i].Cells[1].Text.ToString();
            TextBox Tb = (TextBox)GridView1.Rows[i].FindControl("TextBoxCount");
            decimal total = Convert.ToDecimal(GridView1.Rows[i].Cells[4].Text.ToString());
            cm.CommandText = "INSERT INTO OrderSummary(OrderDetailid,Orders,Count,TotalPrice) values (@orderdetailid,@orders,@count,@total)";      
          //  cm.Parameters.AddWithValue("@orderdetailid",GenerateId().ToString());
            cm.Parameters.AddWithValue("@orders", items.ToString());
            cm.Parameters.AddWithValue("@count",Tb.Text.ToString());
            cm.Parameters.AddWithValue("@total",Convert.ToDecimal(total.ToString()));
            cm.Parameters.AddWithValue("@orderdetailid", Orderno.Text.ToString());            
        }

        cmd.CommandText = "Insert into OrderRecord(OrderDetailid,Name,Email,Contact,Message,Totalprice) values (@orderdetailid,@name,@email,@contact,@message,@Totalp)";
        cmd.Parameters.AddWithValue("@orderdetailid", Orderno.Text.ToString());
        cmd.Parameters.AddWithValue("@name", TextBox1.Text.ToString());
        cmd.Parameters.AddWithValue("@email", TextBox2.Text.ToString());
        cmd.Parameters.AddWithValue("@contact", TextBox3.Text.ToString());
        cmd.Parameters.AddWithValue("@message", TextBox4.Text.ToString());
        cmd.Parameters.AddWithValue("@Totalp",Grandtotal.Text.ToString());
        cmd.ExecuteNonQuery();
        cm.ExecuteNonQuery();
        con.Close();
    }

The variable name '@orders' has already been declared. Variable names must be unique within a query batch or stored procedure.

I am getting this error i am using . I have to insert gridview data in database.