we used to have this, but it ended up with, for example, roboticists taking the biomechanical engineer role and refusing to repair or work on robots, and vice versa.
if the foundation and their duties differ, it should be a different job. if the foundation is the same but the duties differ, it should be an alt title.
machinists, whether they would be "specialized" in robots or biomechanics, both work with the same thing, thus there is no need for an alt-title imo.