My main concern wouldnt be just the training - which would be like one step forward and two steps back
- but more that its a known fact two puppies that grow up together (even those from different litters/breeds) can develop such an intense rivalry that can result in very nasty, constant fights between the two. Some of our members on this board have experienced this and unfortunately had to rehome one of their dogs as this type of fighting is extremely difficult to contain
of course, it;s possible you could be one of the lucky ones, but we wouldnt be being a responsible board if we didnt let you know what we think you could be letting yourself in for if you do decide to take on two pups at the same time