Elephant.io不会发出多个并发请求

Question

I'm using elephant.io in PHP side to emit to NodeJS & socket.io server.

PHP code:

$server = new Elephant(new Version1X('http://localhost:2020'));

$i = 0;
while($i++ < 10){
    $server->emit('myevent', ['id'=>$i]);
}

NodeJS server:

var io = require('socket.io')();

io.on('connection', function(socket){

    socket.on('myevent', function(data){
        console.log(data); 
        // Will be executed just one time {id: 1}
    });
});

io.listen(2020);

As I have while($i++ < 10), it will be exexuted 10 times but in the server side (NodeJS) it just logs the event one time.

Is that regular? Am I missing something? How to make it enable to emit multiple requests?