I was the No.1 on the MAN flight next door to yours. Various airports/ground agents etc have their own way of doing things. A few curious things happen across the network which aren't strictly Easyjet standard. Boarding cards etc would never be anything to do with immigration so asking them would always get the answer you were given and checking passports before boarding is standard. Curiously some passengers, on the MAN atleast, had home printed boarding cards at the aircraft door and whilst I don't actually know why you were re-issued with a swissport boarding card, there will have been a good reason for it.