Hi tio_cristobal,
i did a search on one of my devices and found RPi.GPIO already installed.
root@runeaudio(rw):~# ls /usr/lib/python*/site-packages/RPi.GPIO*
/usr/lib/python2.7/site-packages/RPi.GPIO-0.6.1-py2.7.egg-info
/usr/lib/python3.6/site-packages/RPi.GPIO-0.6.3-py3.6.egg-info:
If it is not installed, try to install it with "pip".
pip install RPi.GPIO
Frank