Free: Contests & Raffles.
Two puppies at the same time will take a lot of work. They tend to teach each other bad habits. I would say two females if I were to get two labs. Female labs by my experience are easier for me to train. Others may have a different opinion. Just in the past the males I have had seemed to have their own itinerary more than the females.
Seth got pretty lucky in my opinion. Anyone who has ever kept two littermates I've ever seen had dogs which are absolute disasters. The pups bond to each other and don't often bond to the owner and establish a decent pack order. I'd wait at least a year preferably two. Give you time to concentrate on getting one to where he/she should be before taking on the next one. Also, spread them out and when they get old, one can be retired or, have workload dimenished and the other will still have some time left in him. just my thought. I'd never do littermates myself as pets. If they were strickly kennel dogs for work maybe.