Datagridview

It looks like, you need to keep on collecting all the Lat, Long pairs for a name (say AZ1) from the DataGrid until you get another different name (say AZ2)
 
If this is the case, then you may try following:
 
        class LatLongPair
        {
            public double Lat { get; set; }
            public double Lon { get; set; }
        }

        private void button4_Click(object sender, EventArgs e)
        {
            Dictionary> LatLongCollectionByName = new Dictionary>();

            List lst = null;
            LatLongPair lPair = null;
            string matchHandle = string.Empty;

            for (int i = 0; i < dataGridView2.Rows.Count; i++)
            {
                if (dataGridView2.Rows[i].Cells[0].Value.ToString() == matchHandle)
                {
                    lPair.Lat = Convert.ToDouble(dataGridView2.Rows[i].Cells[1].Value);
                    lPair.Lon = Convert.ToDouble(dataGridView2.Rows[i].Cells[2].Value);
                    lst.Add(lPair);
                }
                else
                {
                    matchHandle = dataGridView2.Rows[i].Cells[0].Value.ToString();
                    lPair = new LatLongPair();
                    lPair.Lat = Convert.ToDouble(dataGridView2.Rows[i].Cells[1].Value);
                    lPair.Lon = Convert.ToDouble(dataGridView2.Rows[i].Cells[2].Value);

                    lst = new List();
                    lst.Add(lPair);

                    LatLongCollectionByName.Add(matchHandle, lst);
                }
            }

            foreach (KeyValuePair> item in LatLongCollectionByName)
            {
                Console.WriteLine("\n For name : "+ item.Key + ", lat/long vaues are:\n" );

                foreach (LatLongPair lp in item.Value)
                {
                    Console.Write("\t"+ lp.Lat + ",\t" + lp.Lon +" | ");
                }
            }
        }