好吧，我不知道为什么会这样，但是在for循环初始化后添加这段代码解决了这个问题，不仅第一行被复制，而且每一行都被复制：

if (i == dataGridView1.Rows.Count - dataGridView1.Rows.Count)
                        {
                            foreach (var series in chart1.Series)
                            {
                                series.Points.Clear();
                            }

                        }

试试这个-

// filling the columns
    dataGridView1.Rows.Clear();
    dataGridView1.Columns.Clear();

    dataGridView1.Columns.Add("name", "Column1");
    dataGridView1.Columns.Add("budgetedhr", "Column2");
    dataGridView1.Columns.Add("spenthr", "Column3");

    // filling in Rows with some data
    dataGridView1.Rows.Add("Jhon", 21, 23);
    dataGridView1.Rows.Add("Nicol", 31, 2);
    dataGridView1.Rows.Add("Matteo", 23, 41);

    // Now we can set up the Chart:
    List<Color> colors = new List<Color> { Color.Green, Color.Red};

    chart1.Series.Clear();

    for (int i = 0; i < dataGridView1.Rows.Count; i++)
    {
        Series S = chart1.Series.Add(dataGridView1[0, i].Value.ToString());
        S.ChartType = SeriesChartType.Column;
        S.Color = colors[i];
    }

    // and fill in all the values from the dgv to the chart:
    for (int i = 0; i < dataGridView1.Rows.Count; i++)
    {
        for (int j = 1; j < dataGridView1.Columns.Count; j++)
        {
            int p = chart1.Series[i].Points.AddXY(dataGridView1.Columns[j].HeaderText, dataGridView1[j, i].Value);
        }
    }