为什么我的SaveFileDialog再次显示如果取消

我的程序中有一个SaveFileDialog。问题是，当我点击"取消"对话框，另一个SaveFileDialog打开。但是当我在第二个SaveFileDialog上单击cancel时，会出现第三个NOT，所以它不是循环或类似的东西。我看不出是什么原因导致我的SaveFileDialog以这种奇怪的方式运行。显然，我需要解决这个问题，以便如果用户在第一个SaveFileDialog上单击cancel，它将它们返回到表单。

在我的程序中保存的代码如下:

 private void SaveFile()
    {
        if (filepath == null)
        {
            SaveFileAs();
            }
        else
        {
            StreamWriter sw = new StreamWriter(filepath);
            try
            {
                sw.WriteLine(richTextBoxPrintCtrl1.Rtf);
                richTextBoxPrintCtrl1.Modified = false;
                sw.Close();
                lastsave.Text = "Last Saved: " + DateTime.Now.ToString();
            }
            catch (Exception exc)
            {
                MessageBox.Show("Failed to save file. 'n 'n" + exc.Message);
            }
            finally
            {
                if (sw != null) sw.Close();
            }

和SaveFileAs

private void SaveFileAs()
    {
        SaveFileDialog sfdSaveFile = new SaveFileDialog();//Creates a new instance of the SaveFileDialog
        sfdSaveFile.Title = "Save File";//The title of the SaveFileDialog window
        sfdSaveFile.FileName = "Untitled";//The default filename in the SaveFileDialog window
        sfdSaveFile.Filter = "Rich Text Files (*.rtf)|*.rtf|Text Document (*.txt)|*.txt";//The supported file extensions when saving
        if (sfdSaveFile.ShowDialog() == DialogResult.OK)//If the condition is correct, run the lines of code
            try//try to run the code
            {
                filepath = sfdSaveFile.FileName;//get the filepath of the file once it is saved
                SaveFile();//Calls the SaveFile object
                this.Text = string.Format("{0} - Basic Word Processor", Path.GetFileName(sfdSaveFile.FileName));//Set the form name
                lastsave.Text = "Last Saved: " + DateTime.Now.ToString();//Writes the text to the lastsave.Text label, followed by the current date and time
                richTextBoxPrintCtrl1.Modified = false;
                return;
            }
            catch (Exception exc)//Catches any errors
            {
              MessageBox.Show("An error occured whilst saving. " + exc.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
                else if (sfdSaveFile.ShowDialog() == DialogResult.Cancel)
                {
                    return;
                }
        else if (sfdSaveFile.ShowDialog() == DialogResult.Cancel)//If the condition is true, run the line of code
        {
            return;
        }

如果有人能帮我确定为什么会发生这种情况，我将非常感激。

——编辑——

我忘了提到，如果用户确实浏览并保存文件，SaveFileDialog不会打开另一个SaveFileDialog。这与取消SaveFileDialog有关，这会导致问题

DialogResult dialogResult = sfdSaveFile.ShowDialog();
if (dialogResult == DialogResult.OK)
{
}
else if (dialogResult == DialogResult.Cancel)
{
}