Headlights on the overground trains in the UK?

Question

another random question ive always wanted to know-

why is it that when the train is pulling into the platform, the headlight nearest to the platform is always dimmer than the other one ?

Answer 1

Double-dip, like on a car, for use where there are people.

Answer 2

my guess is so that the passengers waiting to get on to train on the platform don't hurt their eyes when the train approaches.