Dwa wątki z C# (HttpWebRequest)

       CookieContainer m_ccCiastkaPoZalogowaniu;
        string m_sTokenM;

private string pobierzToken(string sWtronaWWW)
        {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(sWtronaWWW);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            StreamReader reader = new StreamReader(response.GetResponseStream());
            string kodStrony = reader.ReadToEnd();
            response.Close();
            reader.Close();
            int pozycjaStart = kodStrony.IndexOf("_csrf_token");
            kodStrony = kodStrony.Substring(pozycjaStart, kodStrony.Length - pozycjaStart);
            kodStrony = kodStrony.Remove(0, 20);
            string token = kodStrony.Substring(0, kodStrony.IndexOf("\""));
            token = token.Replace("/", "%2F");
            token = token.Replace("+", "%2B");
            token = token.Replace("=", "%3D");
            //MessageBox.Show(token);
            return token;
        }

                try
                {
                    m_sTokenM = pobierzToken("http://fileshark.pl/zaloguj");
                    string username = "sileent";
                    string password = "dude901";

                    String postData = string.Format("_username={0}&_password={1}&_csrf_token={2}&submit=Zaloguj", username, password, m_sTokenM);
                    CookieContainer tymczasoweCiastka = new CookieContainer();
                    UTF8Encoding kodowanie = new UTF8Encoding();
                    Byte[] byteData = kodowanie.GetBytes(postData);
                    HttpWebRequest postRequest = (HttpWebRequest)WebRequest.Create("http://fileshark.pl/zaloguj");
                    postRequest.Method = "POST";
                    postRequest.KeepAlive = true;
                    postRequest.CookieContainer = tymczasoweCiastka;
                    postRequest.ContentType = "application/x-www-form-urlencoded";
                    postRequest.Referer = string.Format("http://fileshark.pl/");
                    postRequest.UserAgent = "Mozilla/5.0 (Windows NT 6.2; rv:11.0) Gecko/20100101 Firefox/11.0";
                    Stream postRequestStream = postRequest.GetRequestStream();
                    postRequestStream.Write(byteData, 0, byteData.Length);
                    postRequestStream.Close();
                    HttpWebResponse postResponse;
                    postRequest.ServicePoint.Expect100Continue = false;
                    postResponse = (HttpWebResponse)postRequest.GetResponse();
                    tymczasoweCiastka.Add(postResponse.Cookies);
                    m_ccCiastkaPoZalogowaniu = tymczasoweCiastka;

                    StreamReader postRequestReader = new StreamReader(postResponse.GetResponseStream());
                    string resultSource = postRequestReader.ReadToEnd();
                    metroTextBox1.Text = resultSource;
                }
                catch (System.Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }

https://rapidu.net/ajax.php?a=getUserLogin

POST /ajax.php?a=getUserLogin HTTP/1.1
Host: rapidu.net
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0
Accept: application/json, text/javascript, */*; q=0.01
Accept-Language: pl,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Referer: https://rapidu.net/
Content-Length: 36
Cookie: rapidu_session=i1cm7ndhdk0qo35eunkbgjkhm5
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
login=aaaa&pass=bbbb&remember=0&_go=

        private string pobierzToken(string kodStrony)
        {
            int pozycjaStart = kodStrony.IndexOf("_csrf_token");
            kodStrony = kodStrony.Substring(pozycjaStart, kodStrony.Length - pozycjaStart);
            kodStrony = kodStrony.Remove(0, 20);
            string token = kodStrony.Substring(0, kodStrony.IndexOf("\""));
            token = token.Replace("/", "%2F");
            token = token.Replace("+", "%2B");
            token = token.Replace("=", "%3D");
            //MessageBox.Show(token);
            return token;
        }

        private void btnFileSharkLogin_Click(object sender, EventArgs e)
        {
            const string ua = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0";
            const string username = "testk";
            const string password = "testk";
            const string postDataFrmt = "_username={0}&_password={1}&_csrf_token={2}&submit=Zaloguj";
            const string preLoginURL = "http://fileshark.pl/zaloguj";
            const string loginURL = "http://fileshark.pl/login_check";

            CookieContainer tymczasoweCiastka = new CookieContainer();
            HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(preLoginURL);
            HttpWebResponse httpResponse;

            httpRequest.UserAgent = ua;
            httpRequest.Method = "GET";
            httpRequest.KeepAlive = true;
            httpRequest.CookieContainer = tymczasoweCiastka;
            httpRequest.ContentLength = 0;

            httpResponse = (HttpWebResponse)httpRequest.GetResponse();

            StreamReader httpRequestReader = new StreamReader(httpResponse.GetResponseStream());
            string resultSource = httpRequestReader.ReadToEnd();

            string m_sTokenM = pobierzToken(resultSource);

            httpResponse.Close();

            string postData = string.Format(postDataFrmt, username, password, m_sTokenM);
            Byte[] byteData = Encoding.UTF8.GetBytes(postData);

            httpRequest = (HttpWebRequest)WebRequest.Create(loginURL);

            httpRequest.UserAgent = ua;
            httpRequest.KeepAlive = true;
            httpRequest.CookieContainer = tymczasoweCiastka;
            httpRequest.ContentLength = 0;
            httpRequest.Method = "POST";
            httpRequest.ContentType = "application/x-www-form-urlencoded";
            httpRequest.Referer = preLoginURL;
            httpRequest.ContentLength = byteData.Length;

            using (var stream = httpRequest.GetRequestStream())
            {
                stream.Write(byteData, 0, byteData.Length);
            }
            httpResponse = (HttpWebResponse)httpRequest.GetResponse();

            httpRequestReader = new StreamReader(httpResponse.GetResponseStream());
            resultSource = httpRequestReader.ReadToEnd();

            httpResponse.Close();

            richTextBox1.Text = resultSource;
        }

        private void btnRapiduLogin_Click(object sender, EventArgs e)
        {
            const string ua = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0";
            const string username = "testk";
            const string password = "testk123";
            const string postDataFrmt = "login={0}&pass={1}&remember=0&_go=j";
            const string preLoginURL = "https://rapidu.net/";
            const string loginURL = "https://rapidu.net/ajax.php?a=getUserLogin";

            CookieContainer tymczasoweCiastka = new CookieContainer();
            HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(preLoginURL);
            HttpWebResponse httpResponse;

            httpRequest.UserAgent = ua;
            httpRequest.Method = "GET";
            httpRequest.KeepAlive = true;
            httpRequest.CookieContainer = tymczasoweCiastka;
            httpRequest.ContentLength = 0;

            httpResponse = (HttpWebResponse)httpRequest.GetResponse();

            StreamReader httpRequestReader = new StreamReader(httpResponse.GetResponseStream());
            string resultSource = httpRequestReader.ReadToEnd();

            //string m_sTokenM = pobierzToken(resultSource);

            httpResponse.Close();

            string postData = string.Format(postDataFrmt, username, password);
            Byte[] byteData = Encoding.UTF8.GetBytes(postData);

            httpRequest = (HttpWebRequest)WebRequest.Create(loginURL);

            httpRequest.UserAgent = ua;
            httpRequest.KeepAlive = true;
            httpRequest.CookieContainer = tymczasoweCiastka;
            httpRequest.ContentLength = 0;
            httpRequest.Method = "POST";
            httpRequest.ContentType = "application/x-www-form-urlencoded";
            httpRequest.Referer = preLoginURL;
            httpRequest.ContentLength = byteData.Length;

            using (var stream = httpRequest.GetRequestStream())
            {
                stream.Write(byteData, 0, byteData.Length);
            }
            httpResponse = (HttpWebResponse)httpRequest.GetResponse();

            httpRequestReader = new StreamReader(httpResponse.GetResponseStream());
            resultSource = httpRequestReader.ReadToEnd(); //tu pasowalo by spr. {"message":"success","redirect":""}

            httpRequest = (HttpWebRequest)WebRequest.Create(preLoginURL);

            httpRequest.UserAgent = ua;
            httpRequest.Method = "GET";
            httpRequest.KeepAlive = true;
            httpRequest.CookieContainer = tymczasoweCiastka;
            httpRequest.ContentLength = 0;

            httpResponse = (HttpWebResponse)httpRequest.GetResponse();

            httpRequestReader = new StreamReader(httpResponse.GetResponseStream());
            resultSource = httpRequestReader.ReadToEnd(); 

            httpResponse.Close();

            richTextBox1.Text = resultSource;
        }