I personally buy always one of each kind. Maybe I treat them more personally. They R individual for me and when U have two or three they R all the same. It's like U had few friends that were looking the same, act the same and had the same caracters. If someone do this just for collecting than ok, I won't kill him for this. Just I prefer to have only one of each. Even if they R the cuttiest thing in the world. They R getting cutter when they R unique
About fast selling: maybe it's just 'cause there R more and more people here. Community is getting bigger and more Knuffels R sold in short time and there is need of bigger amount of copies.