On Wednesday, 12 May 2021 at 19:41:04 UTC+1, charles wrote:

You have exactly the same situation as any place with two way switching
of the hall and/or the landing light. So it's a common situation to have
two separate circuits at one switch position. So perfectly acceptable
from a regs point of view.
if they are both on the same phase?
I have seen three phases in one lighting switch box. It was a mechanical
workshop with fluorescent lighting and rotating machines.
There was a permanent warning label on the outside.
John