Your going to be busy. I don't have litter mates , but I do have 3 dogs under 2.5 years old, they are pretty close in age and I manage. In the past I have had two puppies that were the same age, but different breeds, it was hard. Back then I didn't do any obedience classes with them and that can make a world of difference. You will have to train the separately on their own and I would also do some obedience with them together. I'm not 100 percent convinced that aggressiveness is 100 percent genetic. When we were younger we went to a farm to get a puppy, a St. Bernard/German Shepherd, mom was sweet(St Bernard) and dad (German Shepherd) was vicious, we couldn't go near him. The puppy was never aggressive and was a wonderful dog.
Misty- Samoyed Mix
Tannor- Golden Retriever CGC
Robyn- German Shepherd CGC, TC
Midnite-German Shepherd CGC, TC
Brennan- Golden Retriever CGC