Hi Pawel,
That's right, there are two drain holes---one outboard and one inboard. Then, in addition, there are two holes close to each other, as you say, about one third of the bumper length from the outside, which I guess are for the light. Not far from that location, there's also the grommet in the body for the wiring.
The right bumper has the same drain holes, but not the additional holes for the light.
Meyer