Don't worry about it. I have littermates 10 mos. old. They love their people as much as they love each other! It is true that when they are quite young, they enjoy each other's company so much that early training can go a little slower. After all, their littermate actually speaks the same language they do! So they distract each other, just like kindergartners do. But the trade off is that some puppies feel lonely without their littermates and may struggle a little with that. The whole idea of bonding has to do with pack behavior. If you think about it, a pack is rarely just two dogs( or wolves or whatever). You just make sure you're the one they both come to for all the "good stuff!" You will become the alpha of your little pack in no time. And they will love you like crazy and love each other too. What could be better?
RUBISH, they will compete for your affection, but will still be friends. My dogs loved each other and comforted each other if they were not well. We lived in Spain for 4 years brought our little dogs with us from England, this was a new experience for them and they supported each other.
hi, I think I'll just share a bit - I've heard the same thing as you about adopting littermates, and as others have said that seems to be a fallacy BUT I have sold 2 brothers to a family and they did say that housebreaking had to have some separate attention. How's that part going for you?