Multiple endpoints cannot be deployed using the same path

Question

I tried to create a simple chat project with two users

but I get an exception like

javax.servlet.ServletException: javax.websocket.DeploymentException: Multiple Endpoints may not be deployed to using the same path [/websocket]

in catalina.out

Here is my source file

   @ServerEndpoint("/websocket")
    public class ChatEndPoint {

        @OnMessage
        public void message(String message, Session session) throws IOException, EncodeException {
            //processed the message
        }
   }

I ran the project on the server from eclipse kepler, with oracle java 7 on ubuntu 13.10

Already tried to clean existing tomcat projects, but the problem is still not resolved.

What to do to resolve this type of error.

This is my first experience with WebSockets.