This is my guess:
The people who have opted in for next business day 9 am delivery and delivered their package on 31st December at Purolator office, the delivery stamp was 9:43 am on 4th January and it would be the purolator driver who have delivered it. It would be the 700 batch. The mystery still remains whether the delivery was actually done at 9:43 or during the afternoon.
The people who opted in for same day delivery, some local agents might have delivered it on purolator's behalf and some of their's credit card has already been charged.