Recording twice in txt file

Question

I realized with the coding I have here.. when the count =4, the text file will record twice.. once with the "time" and once with both "time+string".. How can i avoid this? 

I expected that when count =4, record "time+string" only..

 

private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e)

        {

            string time = DateTime.Now.ToString("dd/MM/yyyy HH:mm:ss.ff");

            RxString = serialPort1.ReadLine();

            string[] split = RxString.Split('.');  //split RxString at '.'

            string dp = split[1];                 //dp contains digit behind '.'

            Char c = dp[0];                      //c = first decimal place

            split[1] = c.ToString();

            RxString = split[0] + "." + split[1];  //Re-combine Rxstring

            this.Invoke(new EventHandler(DisplayText));

            string path = @"C:\\Users\acer\Documents\Data3.txt";

            string[] number = RxString.Split(' ');

            string unit = split[1];

            if (x == unit)

            {

                count++;

                string time2 = DateTime.Now.ToString("HH:mm:ss.ff");

                string data2 = time2 + "\r\n";

                File.AppendAllText(path, data2);

            }

            else

            {

                count = 1;

                x = unit;

                string data1 = RxString + "\r\n";

                File.AppendAllText(path, data1);

            }

            if (count == 4)

            {

                string data = time + "      " + RxString + "\r\n";

                File.AppendAllText(path,data);

                count = 0;  //reset count

            }