If they were beagles,or squirrel dogs no. But two Lab pups at one time is a handfull and may be too much for any amateur trainer once they start growing. Also, unless very well trained, two retrievers in the same blind or boat is asking for trouble.
As for male or female; one won't be any better than the other. Just different. A female may be easier to train and work with for a first time retriever or hunting dog trainer. A well trained mature male will have a certain physical "edge" that I prefer. But a female can have just as much fire and desire.
I always go with male hunting dogs. I prefer that ballsy edge that they can exhibit.
I have trained hunting dogs for forty years and know what to do when a male hits that period between 12 & 18 months where they put you to the test of wills. The period where alot of amateur trainers give up and fail to bring a dog up to its bred-in potential.
I would recomend a female pup for the first time, or realatively inexperienced hunting dog trainer. Unless you plan to have it professionally trained by someone. Then it really doesn't matter.