Roger, yes, I understand that they have the same Julian Day. I'm not sure you are getting my point about the average initial quake occurring in the middle of the day, (some before, some after), so that, on average, only half as many quakes are counted. A quake that occurs at 23:00 only looks for quakes in the next 1 hour; a quake that occurs at 01:00 looks across 23 hours, .....
Chris