Raising littermates has two major challenges, the bonding and the training.
Some people just assume that no one is smart enough or capable enough to deal with the challenges and say littermates should never be raised together, but neither issue is impossible, just a bit more work.
You should certainly look for as many ways as possible to do things individually with the dogs and get them used to being away from each other for periods of time. Their natural instinct will be to bond with each other more than with you, but you can work on increasing their human bond by doing things like hand feeding and separate walks and having you and your wife each play with and train a puppy in a separate room, taking turns with each dog. Most of this you will only have to do while they are puppies, until you know they've formed a strong bond with you and your wife.
The training is more intensive, basically having to do everything four times instead of one, once with each individual dog, then again with each dog while they are together. You can work on as many commands as you feel they are capable of when they are separated, but I'd only work on one of them at a time while they are together until they've really got it. So you could do sit, down and stay while they are separate, but only work on 'sit' together until they always do it every time before moving on to 'down'. It will be much harder for them with the other one around distracting them so you'll need a lot of patience here. You also have to preface every command with their name so they know which dog it's intended for. I have four dogs, and they have 'name commands' but when I want them all to come or all to sit I have a group name (in my case it's "Puppies")
Try to find something that REALLY motivates them (I make homemade treats that dogs will do ANYTHING for) and interrupt their play occasionally and make them come to you for it. When I was teaching mine to come right away when called I would give the first three dogs that arrived a treat, but not the last one. It only took one afternoon for them to get that they better come FAST when I call
My Chins are from different litters but are one week apart in age and have been raised together from 10 and 11 weeks old. They get along perfectly...but they are definitely "people" dogs. As long as you are aware of the special issues and you feel you are up to the extra work involved, there is no reason not to have littermates.