Could the different approaches to the queue problems be partly to do with the location of the actual voting room. If it is next to a easily accessible area it might be very difficult to close off an area properly with the people properly isolated.
Two possible reasons for the queues:-
1) Labour voters having to get some 'Dutch courage' before voting.
2) It takes time for a person to vote 20 times. They cant vote again too quickly or they'll be recognised.