How to avoid nginx+passenger logging each request two times

Question

I have nginx(0.7.64) with passenger(2.2.9) over ruby(1.8.7) Enterprise Edition.

When I operate from script/console, log behaves normal, but whenever nginx receives a request, it is logged twice.

I have two different rails apps in separate vhosts (like the one bellow) and it happens in both (one is in development and one in production).

server {
  listen 80;
  server_name my_app.dev;
  root /home/fer/my_app/public;   # <--- be sure to point to 'public'!
  passenger_enabled on;
  rails_env development;
}

The nginx config file is quite default:

user  fer;
worker_processes  1;

events {
    worker_connections  1024;
}

http {
    passenger_root /usr/local/lib/ruby/gems/1.8/gems/passenger-2.2.9;
    passenger_ruby /usr/local/bin/ruby;

(...original contents...)

    include /opt/nginx/conf/sites-enabled/*;
}

Can anybody point me to a solution?

Thanks