Contradiction IN daysim schedule

I have defined an occupancy program for the occupany file(daylight RUN) for 8 to 18 hours, but when I look at the output results of the Lighting Daysim program, it is two hours longer(schedule), i .e it lasts for 8 to 20 hours. Please explain the reason for this to me, thank you .

green panel : occ_schedule
yellow panel : lighting schedule