Facing two puppies from the same litter often results in what is known as littermate syndrome. The puppies will bond with each other and this will make them less likely to join you. Dogs may not hear you and it will be much more difficult to train them. There is no easy answer to this.
There are cases of two women who get along well throughout their lives, some get into some minor dispute, and cases of women who hate each other at some point in their lives to the point of suffering serious injuries. There are too many variables to reach a conclusion. Most training professionals strongly recommend not adopting two puppies at the same time. The biggest challenge of adopting two new puppies is their tendency to bond very closely with each other, often excluding a meaningful relationship with their humans.
In addition, owners often underestimate the time commitment required to properly care for and train two puppies; as a result, puppies often end up untrained and poorly socialized. Littermate syndrome can affect dogs of any breed, and it can also affect unrelated puppies that are adopted at the same time and raised together. Even though they were littermates and you can assume that there is some element of familiarity, it would be best to work with them as if they weren't and take every precaution. When visiting a breeder, prospective puppy owners may find it difficult to choose a puppy from the litter.
Training two puppies from the same litter may take longer than expected because puppies are very distracted from each other. At first, puppies with littermate syndrome may seem to be misbehaving or need obedience training. Many owners of puppies adopted at the same time ultimately feel disappointed in their relationships with their dogs, even when they commit to providing for them for life. When a family was given 2 dogs from the same litter to breed, on each occasion, at least one of the puppies was considered temperamentally unfit for work, even though both dogs began to be fully capable.
Consider adopting a puppy now and another later, or better yet, a puppy now and an adult dog later. I also found the article irritating and scolding and it didn't take into account the human influence on dogs, littermates or otherwise, nor the factor of being a strong pack leader. Puppies with littermate syndrome only interact with each other and become highly dependent on each other for a sense of security and normalcy. If you have misbehaved sibling puppies (or are thinking of training two puppies from the same litter together), keep reading to learn everything you need to know about littermate syndrome in dogs.
The presence of another dog also stops puppies' ability to bond with their owner as you expand the puppy package and allow them to trust each other rather than you and your family. Littermate syndrome makes training two puppies from the same litter especially difficult, Graddy says.