Brongersmai and Curtus both occur on the island of sumutra, but they are seperated by a mountain range.
Breiteinsteini occurs on borneo.
here is a range map i made from reading a lot of literature:
http://redpython.net/newsite/The%20C..._files/map.jpg
there are other differences between the species besides location, hence why they are different species and no longer subspecies.