Now with the above facts in mind, which do you think is safer?

Ehsjr-

You are rationalizing. The need for the light is greatest in the event of a
fire. With two bulbs in series, the resulting light is weaker and harder to
see in dense smoke.

Most of the time you won't have a fire. You could carry your rationalization
further by eliminating the lights and having zero chance of accidental
electrocution or falling from the ladder, and save on the electric bill to
boot.

Good Luck.

Fred