My two white Schnauzer/Poodles are Brothers and littermates. I got them when they were 12 weeks old.
I kept them in separate crates until they were 6 months old. They slept side by side in the kitchen in their crates until then. Then I moved them to separate rooms at night. Leeo was in my room in his crate ... as he was my dog. Blu Boy was in his crate in my late Mothers room ... as he was her dog.
I potty trained them together. I had them eat side by side to avoid food aggression. They had play time and walks together.
I gave them separate human time also. Their training was sometimes separate. But I always trained them side by side when it came to sharing food and toys.
It IMO is super important that they realize that being together brings good things. Mine only ever had one squabble in their lifetime together.
After they were one year old and trustworthy they began to stay together alone in a puppy proofed house when we went away. They still slept in separate bedrooms at night.
Remember that raising two pups together can be frustrating at times and more than double the work! ... Not to mention double the food and vet bills. But ... I love challenge ... so raising the two of them was great fun for me! I also was retired and could do all of this 24/7.
I was lucky (or just did it all correctly) and I ended up with two wonderful dogs who did not have littermate syndrome.
