Two puppies at the same time are not recommended, for a couple of reasons -- they can bond more closely with each other than with you, and hence be harder to train, and also, it is very hard to properly train two puppies anyway. This would be a serious concern if no one is home all day (I hope someone will be able to check in at least midday with the pup, as they cannot hold themselves for a whole day; if the pup is 8weeks old, it really needs to be taken out every two hours or so. If left alone all day, you will have a long housetraining road ahead, just be aware of that and factor it in). Most breeders recommend waiting til the first dog is at least a year old before getting a second. If no one is home all day, I would recommend getting a second dog eventually -- cavaliers are very strong 'people' dogs, and can get very lonely left alone for 8 hours or so a day.
Generally, be sure to read up on ways to keep a puppy/dog entertained on its own all day. Of course, this breed needs to remain inside primarily as they are not garden breeds and run a serious risk of being stolen and can be escape artists. It will be way too cold for a puppy to be outside for any length of time until the weather warms in spring (I got my first pup on Dec 31st and remember it took til he was nearly 6 months old to have enough coat to keep warm on cold day walks). Also the pup will need to be in a very safe environment when alone -- no cords accessible, nothing that you don't want chewed, no ability to get into cupboards (eating simple household basics like chocolate or raisins can kill a dog, especially a puppy the size of a cavalier). Leave a radio or TV on, leave *safe* toys (nothing that could choke, tangle around limbs or neck, be swallowed).
Some people are successful with two pups at the same time but this will take a lot of extra work and commitment. If you are ready for that, and can also get home daily at least once during the day and preferably twice (If you can't get home I\'d strongly recommend looking into day boarding for the dog or paying someone else to check in midday every day, eventually to take the dog for walks etc), then you might consider this. Just be aware of the level of work. I found ONE puppy so exhausting that when I got my second I opted, like a lot of people, for an adult. I just couldn't face the whole housetraining rigamarole so soon after going through it once, and also, having a puppy while fun is very limiting to your own life for the first year becasue they are bbabies, needing time and training of all types. I could not get out of the house for longer than 2-3 hours at a time for the first two months as part of the housetraining process. Puppies really need people to be be there with them as much as possible, just like babies, for the same reasons.