Can an employee be called Recruiter cum Trainer?

In today's economic times of role optimization, there is a growing trend of rolling different roles into one. So yes, I have seen companies appoint people as Recruiter cum Trainer or vice-versa. Others give you a more generalist title like HR Specialist and then make you do all that is on the table!

Yes, why not? It depends on his responsibilities.

Yes.  Organizations are cutting down manning cost by rolling down several positions and responsibilities in one maximizing the full potentials of every employee.