qt c++ multiple definition of `peerlist'

/****************************************************************************
**
** Bit Coin Faucet Web Socket Server C++ QT
**
****************************************************************************/
#include "websocketserver.h"
#include "QtWebSockets/qwebsocketserver.h"
#include "QtWebSockets/qwebsocket.h"
#include <QtCore/QDebug>
#include "faucetcore.h"


QT_USE_NAMESPACE

//! [constructor]
EchoServer::EchoServer( quint16 port, QObject * parent )
    : QObject( parent )
     , m_pWebSocketServer( new QWebSocketServer( QStringLiteral( "Echo Server" ), QWebSocketServer::NonSecureMode, this ) )
     , m_clients()
{
    if( m_pWebSocketServer->listen( QHostAddress::Any, port ) ) {
        qDebug() << "Echoserver listening on port" << port;
        connect( m_pWebSocketServer, & QWebSocketServer::newConnection,
        this, & EchoServer::onNewConnection );
        connect( m_pWebSocketServer, & QWebSocketServer::closed, this, & EchoServer::closed );
    }
}
//! [constructor]

EchoServer::~EchoServer()
{
    m_pWebSocketServer->close();
    qDeleteAll( m_clients.begin(), m_clients.end() );
}

//! [onNewConnection]
void EchoServer::onNewConnection()
{
    QWebSocket * pSocket = m_pWebSocketServer->nextPendingConnection();
   
    connect( pSocket, & QWebSocket::textMessageReceived, this, & EchoServer::processTextMessage );
    connect( pSocket, & QWebSocket::binaryMessageReceived, this, & EchoServer::processBinaryMessage );
    connect( pSocket, & QWebSocket::disconnected, this, & EchoServer::socketDisconnected );
   
    m_clients << pSocket;
    //peerlist.;
    //qDebug() << m_clients.count();//wyswietla ilosc klientow
    //qDebug() << m_clients.takeFirst();
    //qDebug() << pSocket->peerAddress();
    //qDebug() << m_clients;
    testDebug();
   
}
//! [onNewConnection]

//! [processTextMessage]
void EchoServer::processTextMessage( QString message )
{
    QWebSocket * pClient = qobject_cast < QWebSocket *>( sender() );
    if( pClient ) {
        //qDebug() << "Message: " << message;
        pClient->sendTextMessage( message + " echo server" );
    }
    //m_pWebSocketServer->close();
    qDebug() << pClient->peerAddress();
   
    //qDebug() << pClient->localAddress();
    //qDebug() << pClient->requestUrl();
    //qDebug() << pClient->;
    Q_FOREACH( QWebSocket * pClient, m_clients )
    {
        if( pClient ) //don't echo message back to sender
        {
            //qDebug() << pClient->peerPort() << endl;
            //QString q =  pClient->peerAddress().toString();
            //pClient->sendTextMessage(q);
            //qDebug() << q;
        }
    }
}
//! [processTextMessage]

//! [processBinaryMessage]
void EchoServer::processBinaryMessage( QByteArray message )
{
    QWebSocket * pClient = qobject_cast < QWebSocket *>( sender() );
    if( pClient ) {
        pClient->sendBinaryMessage( message );
    }
}
//! [processBinaryMessage]

//! [socketDisconnected]
void EchoServer::socketDisconnected()
{
    QWebSocket * pClient = qobject_cast < QWebSocket *>( sender() );
    if( pClient ) {
        m_clients.removeAll( pClient );
        pClient->deleteLater();
    }
}
//! [socketDisconnected]