Nothing wrong with having two Lives at a light switch, just make sure that it is marked up on the CU "upstairs lights, downstairs lights". If the next person is working on the upstairs ceiling rose, guess what MCB he needs to turn off??? If working on the light switch he needs to turn off both!
I install up and down stairs hallway lights separate as standard, have done for ages. Never had any problems.
I install up and down stairs hallway lights separate as standard, have done for ages. Never had any problems.