One Bird or Two
With a buddy, will they not be as attached to the person? Probably not, but that depends on what type of attachment the person wants. It also depends on how flexible the owner is. We have birds we keep together 80% of the time, but if one starts guarding the other or gets overly territorial, then I am sure to have a spare cage to separate them for a time. We also have our birds that share a day cage in separate sleep areas. One sleeps in the cage and the other sleeps on the play top. Read about sleep cages by clicking here.
If someone wants 2 birds, I usually recommend that someone gets that first baby and develops a really tight bond. Then about 6 months later, get another (if they want two), and if they are not interested in breeding, that they get the same sex.
The first bird will have started bonding to you, and it will teach the new baby, which can be the same species or a similar-sized but different species. This second baby will often bond more to the first bird than to you because it hasn't had time alone with you like the first. I have had people keep their two birds separate until the second bird develops a tight bond too to their human.
But even if that second bird does bond tighter to the first, that can be a good thing. You do want them to enjoy each other, and it will reduce their neediness and demands on you. I don't really want them to be so clingy to me that they are constantly wanting to be with me, which a single bird will do unless you teach them as babies how to play by themselves.