__construct being called twice on custom page

class MyPage extends Page
{
  public function __construct()
    {
      Debugbar::info(microtime());
    }
}

class MyPage extends Page
{
  public function __construct()
    {
      Debugbar::info(microtime());
    }
}

class MyPage extends Page
{
  public function __construct()
    {
      Debugbar::info(microtime());
    }
}

class MyPage extends Page
{
  public function __construct()
    {
      Debugbar::info(microtime());
    }
}

This will output two results:
0.55048200 1680612812
0.55084500 1680612812

Why is that and how to fix it?