copy captcha

Question

You can use the WebClient to download the image by feeding it the url of the php link as such:
System.Net.WebClient client = new System.Net.WebClient();
// download file
client.DownloadFile("<<url>>.php", "<<destination file>>.jpg");
// retrieve file bytes
byte[] imgBytes = client.DownloadData("<<url>>.php");

This is good, but this downloads a second and new captcha that doesnt work with the posting. I need the exact same captcha that was generated with the form.

 

Plz reply