I just want to say that while I think crating the two together is a terrible idea, I initially misread the title of this thread as "Can I create new pup with old dog?" and that would have been an even worse idea.
You're not a fan of cloning?
Crating two dogs together is a very bad idea in general.
Personally, I don't even leave two dogs together unsupervised at all. Plenty of people do, but that is after they know their dogs very well. Many people (like me) err on the side of caution and simply separate when the dogs are unattended. Even friendly and playful dogs can either play too rough and get hurt that way, or have a small spat which escalates when there is no human to play referee.
You're getting a Cane Corso. You sound really really unprepared for the demands of the breed. I don't know all that much about them honestly, but I do know they aren't exactly the simplest of dogs for newer owners. Major socialization is required, careful introduction of new people and dogs, plenty of exercise (they are working dogs after all) and solid training. And since your previous posts indicated that you may have gotten the dog from a less than reputable breeder, he may already be behind on socializing and might not have the best temperament genetics behind him.
Find a GOOD trainer NOW. Someone with experience with working dogs/Molossers/bullies and similar. There's a gorgeous and well socialized young Cane in my current group obedience class, they have WORKED to own a wonderful dog and are continuing to do so in terms of training. PetSmart etc might not be the best place to find a suitable trainer; heck, PetSmart doesn't even allow bully breeds in its daycare (regardless of temperament testing- no pit bulls or pit bull mixes or anything that looks like a pit bull) so how much experience do many of its workers have with them?