The second reading is normally lower than the first. Unfortunately, it's not accurate - must have something to do with the compression of blood vessels by the cuff. You normally have to wait 5 or 10 minutes to take another reading on the same arm, which is why medical professionals who want to get a second reading will normally take it using the other arm.
Sorry - I used to be optimistic about the second reading also!
Well I would say the longer you rest the lower the blood pressure. Also you can get two different reading from the left side to right side. Why do you take your blood pressure so much at one time? If you work out or jump up and down your bp will rise. I always check mine while working out to achieve my optimum bp.
Do you worry what your readings will be? My first reading is ALWAYS higher (at home with the Omron monitor)then the second reading. Sometimes the third reading is even lower, and sometimes its close to the first reading again. Sit there for about 15 minutes, take deep breath, and your readings after the first reading should be fine.
A Hypertension Specialist told me one time that even people who have normal blood pressures there BP is not always exactly the same, it can vary from minute to minute sometimes.