I have an intelligence center on my main base. With 40 scientists (5 for HQ, 5 for Bio Lab, 5 for Intelligence center, 25 for Science lab)
I can't build the advanced one over the normal one (facility is in use... even if at this moment nobody was interrogated but scientists maxed)
But I can build an advanced one in the base in addition to the normal one which is in contradiction with the Ufopedia.