I have 4 dogs, and only 2 of them stay together when they're home alone.
The 2 who are together, stay downstairs in a room I have set up just for them--toys, an old futon, water dish, and a radio.
The other 2 stay upstairs, but not together, a gate separates them.
My 2 females have fought before, and I will never trust them alone together--it's too scary to think about what could happen.

With yours being so young though, I'm sure if you follow the trainer's advice, and socialize them, they will be able to stay together someday.