We haven't been able to be successful in creating a clone that has the ability to live a normal lifespan as it's other genetic counterparts. And cloning is a process that usually involves three organisms of the species. We have to harvest a cell from a cell donor, insert it into an ennucleated egg (egg without a nucleus) from an egg donor then place this embryo into a surrogate mother. Risks of miscarriages usually are quite high and furthermore the genetic makeup of both clone and the cell donor will be genetically identical. We need genetic diversity in order for a species to survive...plus I'm not sure if Rhinos can "inbred", if you were to call it that.