prevet logging in with name of existing player

i tried this, but it doesn't work if someone log in with my name, he gets kicked, but it unlog me :/
it seems like PlayerPreLoginEvent is called twice

PHP:

public function onPreLogin(PlayerPreLoginEvent $e){
        $player = $e->getPlayer();

        foreach($this->getServer()->getOnlinePlayers() as $p){
            if($p !== $player && strtolower($player->getName()) === strtolower($p->getName())){
                $e->setCancelled();
                $e->setKickMessage(TextFormat::RED."The same nick is already playing");
                return;
            }
        }

        $this->unauthed[strtolower($player->getName())] = $player;

    }

i tried change pocketmine method too (method runs before PlayerLoginEvent) but PlayerLoginEvent is still called -,-

PHP:

foreach($this->server->getOnlinePlayers() as $p){
            if($p !== $this && strtolower($p->getName()) == strtolower($this->getName())){
                if($this->kick(TextFormat::RED."The same nick is already playing")){
                    $this->close($this->getLeaveMessage(), TextFormat::RED."The same nick is already playing");
                    return;
                }
            }
        }

Why do you think that it's called twice?

because it kicks player and unlog already plaing player

Unlog? But isn't it something that only your plugin does?
Add echo lines at critical points to log the control flow.