There are many reasons not to do two at once. I have done it, but I am set up for it. It is a lot of training classes, a lot of socialization both singly and together. And overall a lot of work.
If you have to ask, than it's not a good idea -- not with everything, but with raising two puppies at the same time. Once you have raised three or four dogs to the point where you want them to be (after they are full grown), then you have a much better idea what it takes to raise up and train one dog. Two brings its own set of challenges.
It is NEVER a good idea to buy a pet for a pet. It is the people (you) who will have to feed, vet, train, exercise, board, and bury the new dog. Reasons for getting another dog should be because the people (you) want a new dog. That is normally the case anyway. But, you also have to ask yourself if you are ready for the added work and cost, and what it is you want the new dog for that the old dog cannot provide.
If you still want to raise two puppies at once, here are some things to consider or plan for:
1. puppy classes. When you have two dogs it is MUCH more important that they are well trained. Both the new pup and the older pup should be in separate classes at least once a week probably for a year. And then occasionally.
2. boys and girls are capable of contributing to pregnancy prior to 1 year of age and this MUST NOT HAPPEN. So, do you have a plan for managing the heat cycle?
3. Your puppies need to be socialized inside your home and outside of your home in many different locations/situations, this should be done both singly and as a pair, so this is not twice the socialization, but three times the socialization. There is a good reason for this. Puppies get their confidence from their pack, so all the experiences as a pair do not count as working toward being socialized when they are in a situation on their own. Dogs that are always together with a pack member can literally freak out and become another dog without their buddy with them. You do not want to find out that this is the situation when your dog is going to the vet. So you have to train and socialize separately. But dogs can also act differently when they are with a pack member, so you really have to do it together too if you intend to take them places together.
4. Male/Female, they should not have any problems with each other down the road, but you never can tell. I would suggest looking up NILIF and start now if you haven't already. Strong, consistent leadership will eliminate some problems before they start. You do not want to suddenly have an 11 month old pup and a 14 month old pup that are putting bloody holes in each other. Probably won't be a problem, it may start closer to two, it is best to live in such a way as to avoid the issues, but if it does happen, you will need a plan.
5. Old age. Hopefully your dogs will have many years with each other and you. I am hoping that you suffer the veterinary expense of two geriatric dogs, that is the best case scenario. However, as the pups will be strongly bonded, if one of them does die suddenly or early, that can take a tremendous toll on the surviving pup. Some dogs do not overcome it and follow their mate shortly afterwards -- usually with older dogs. And the grief of losing two dogs close together is hard. But because they are so close in age, we have to almost hope for that to happen in a dozen years or so.
RIP Arwen, CD RN CGC
RIP Whitney, RN CGC
Jenna, RN CGC
Babs, CD RA CGC Herding Instinct Certificate
Heidi, RA CGC
Tori, RN CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC
Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly & Bear