Why c# datagridview returns double records?

Hi,

I have a datagridview that I need to populate data from sql server.Here is the code.

using (SqlConnection con = new SqlConnection(constring))
        {
            using (SqlCommand cmd = new SqlCommand("SELECT * FROM Customers", con))
            {
                cmd.CommandType = CommandType.Text;
                using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
                {
                    using (DataTable dt = new DataTable())
                    {
                        sda.Fill(dt);

                        //Set AutoGenerateColumns False
                        gfDataGridView1.AutoGenerateColumns = true;

                        //Set Columns Count
                        gfDataGridView1.ColumnCount = 87;



                        gfDataGridView1.DataSource = dt;

                    }
                }
            }
        }  

This code returns me 87 columns (first 87) with totally empty and 87 columns with real data from database.How can I avoid these 87 empty columns?

Thanks