One of the services I offer to my clients is a "new dog package," which includes a consultation to help the owners determine what type of dog may be best for them - breed, sex, age, grooming requirements, activity levels, etc. Sometimes, a puppy is the right candidate, but I NEVER recommend getting two puppies at the same time or from the same litter. Many breeders (good breeders, anyway) will not adopt two puppies out to the same household. Why is this?
I have my reasons, which include: a) two puppies are 7x the work of one puppy and b) some of the toughest behavior modification cases I've handled have been for clients who have attempted to play the "multiple puppies at one time" game. A lot of people think "raising two puppies will be easier than one. They can keep each other occupied!" If you believe this, definitely seek out a mother of human multiples - twins, triplets, quadruplets, and tell her your theory. Trust me, her responses will be enlightening!
Here are some potential problems with raising two littermates:
Your puppies will not likely be able to hold their bladder or bowel movements overnight. They may also not have mastered the art of "synchronized defecation," which means one puppy may decide to loudly request you let her out of her crate for a potty break at one a.m. and your other puppy may decide, "you know what? 3 a.m. works much better for me." With one puppy, you may need to get up once in the night. With two puppies, plan on getting up at least four times. Also, sometimes that crying doesn't mean, "I want to potty!" sometimes it means, "Hey, I want to play with my sister NOW!"
Each puppy will need a lot of individual time with the family. They should spend much more time separated than they spend together, and they will loudly complain about this at every possible opportunity. You should plan on attending separate puppy classes, giving separate walks, having separate puppy socialization adventures, separate potty breaks, separate trips to the vet's office, etc.
I have never seen a puppy teach another puppy any of the following: sit, down, reliable name response, targeting, focus, or how to pass a CGC. I have, however, seen dogs teach one another that eating poop is fun, counter surfing is fun, barking is fun, digging out from under the fence is fun, whining and barking in the crate is fun, jumping on guests is fun, and that chasing cats or other small animals is really fun.
Aggression - some of the worst aggression cases I've seen have been between two littermates. While this usually happens when dogs enter adolescence and are not yet fully physically, socially, or mentally mature, it can happen even sooner. This is most frequent in same-sex pairings but may happen in male/female pairings as well. Anecdotally, I see this the most commonly in bully breeds, terriers and guardian breeds, followed by herding breeds, but it can in any littermate pairing, including those who are toy breeds, "friendly" breeds, or mixed breeds.
Intense bonding can create problems - it is not uncommon for littermates to develop separation anxiety problems from each other, where each dog only feels "complete" when his littermate is present. This can be a very, very tough challenge to fix!
Puppies are expensive. Two puppies are more expensive than one puppy. I'm not talking about purchase price - you also need to double food bills, vet bills, equipment expenses (collars, leashes, harnesses, crates, toys, etc.), dog walking/pet sitting expenses, training expenses (puppy class), etc. You may also want to consider the cost of: medical treatment for your own insomnia, hair dye (to cover the greys which may pop up!), and expanding your current red wine/chocolate/massage therapy/mani-pedi budget - you will need some de-stressing and decompressing! Also, you may need to replace twice the number of expensive high heels, jeans, cell phones and cables, and other things that puppies love to destroy, so make sure you budget that into your plans.