If I read your post correctly, you do not have chickens yet. You do not have a flock at home. If I have that right, then I would not worry about it too much unless your are getting a huge amount of chickens. The more chickens you get the more money you have tied up in them, and a bigger risk.
Quarantine is really to protect the flock you have at home. You do not want to bring in a disease, and wipe out your whole flock. However, by mixing two different flocks, you do run the risk of one flock infecting the other flock, and winding up not having a wonderful chicken experience, but a bunch of sick birds.
imho - you need to be a little bit heartless, do not take or buy anything that looks the least bit raggy or sick. For the most part, although not always, sick birds look sick.
If I was talking about 5-6 head in one flock and 5-6 head in the other flock, and they looked pretty healthy to me, I inspected their housing, and it looked fairly decent with healthy animals, I would put them all together.
I think if you put them all together in a strange place to all of them, while you will have a few pecking order scuffles, it should not be too bad, and get over quickly.
Mrs. K
ps. if one of two dies, I feel bad for a bit, but I do get over it. Some people have a hard time with this, and if you are like that, then you should be more careful.