为什么不删除多余的重复字符串，只保留唯一的值？

的数据

List<uint> codes = new List<uint>()
{
    { 130001 },
    { 130001 },
    { 130002 },
    { 130002 },
    { 130002 },
};

DataTable table = new DataTable();
List<DataColumn> keys = new List<DataColumn>(2);

DataColumn personalColumn = new DataColumn()
{
    ColumnName = "Personal",
    DataType = typeof(uint)
};
DataColumn countColumn = new DataColumn()
{
    ColumnName = "Count",
    DataType = typeof(int)
};

table.Columns.Add(personalColumn);
table.Columns.Add(countColumn);

keys.Add(personalColumn);
keys.Add(countColumn);

table.PrimaryKey = keys.ToArray();

codes.Distinct().ToList().ForEach(code =>
{
    table.Rows.Add(code, codes.Where(x => x == code).Count());
});

dataGridView1.DataSource = table;

字符串