We have two dogs, adopted about 9 months apart. We love them both, but having two is more work for sure, and makes travel a lot more difficult (it's easier to ask someone if you can bring one dog with, but two is a lot, though ours are bigger at about 40 lbs).
They tolerate one another, and play some, but I think they'd both be fine as only dogs. We are gone for 8-10 hours a day, and so it's nice that they have each other, but I think they just sleep regardless. They get jealous of each other, and fight for our attention. Training is a lot more difficult with two too. I would recommend waiting, since yours is a puppy, and bonding more with it. You can always add a second dog down the road, but right now you can focus all your time and energy on him, get him socialized and trained. I've heard that you shouldn't adopt two puppies at the same one because they'll bond with each other rather than you (don't know if this is true or not).