error while copying file from one place to another

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C#

i am trying to copy a file from one place to another here is the code.

private void button1_Click(object sender, EventArgs e)
{
    OpenFileDialog openFileDialog2 = new OpenFileDialog();
    openFileDialog2.InitialDirectory = @"C:\";
    openFileDialog2.Title = "Browse Text Files";
    openFileDialog2.CheckFileExists = true;
    openFileDialog2.CheckPathExists = true;

if (openFileDialog2.ShowDialog() == DialogResult.OK)
   {
       textBox2.Text = openFileDialog2.FileName;
   }
string filename,filex;
   filex = openFileDialog2.SafeFileName;

   filename = textBox2.Text;
   string dpath = @"D:\G\"+ filex ;
   File.Copy(filename, dpath );

but it gives me the follwoing error
The file 'D:\G\openFileDialog2' already exists.
please tell me whats wrong with the code.