I got an answer from the city ... "It's a corner lot so it has two addresses. As the city is conserned the primary address is Pitkäkatu 32 and secondary Mäntykatu 1. The official address of the building has always been Pitkäkatu 32, so that's why that address is visible in the city map service and on national land survey (Maanmittauslaitos) maps. Access seems to be arranged via Mäntykatu, but obviously the address hasn't been defined based on access, instead the primary address of the lot itself has been used. In these kind of cases the address of the building isn't changed by the city unless they get a request from the owner."