Kamagong is not in the same family as Mahogany. Indigenous to the Phillipines and Indonesian islands, it is more commonly known as Macassar Ebony. It can be referred to as black wood, or one of the many "ironwoods", but never black mahogany.
Narra used to be plentiful in the PI; it's actually their National Tree. As Joey made reference to, it is an extremely heavy, dense, unstable wood that is now on the Endangered list. Last time I saw a cm of this stuff, it was close to $1000.00. Prone to cracking when cured, it polishes beautifully and used to be a premium choice for hi-end furniture and flooring.