Well, some plants in Bauhinia seem to only grow from cuttinhs, others from seed.
Evidence of them fix nitrogen seems to be mixed.
As long the parts you use as mulch are not viable,they should be fine, and not compete with your plantings.
Btw, it seems that many Bauhinia are edible,check out this Eat the Weeds entry:
http://www.eattheweeds.com/bauhinia-pretty-eats/
