I am almost sure that Accor Group has been doing the same thing for nearly ten years, at least in Europe, mostly in France.
There are lots of block buildings with inside a Suite Novotel, an Ibis and an Etap Hotel (now Ibis Budget), all under the same roof.
In the Accor way there are different "receptions" and corridors are separated, so you can't go to the other brand without exiting the building.