The A380 has 20 main and 2 nose wheels. Apparently the nose wheels have no brakes (compare with Are there any aircraft with a nose wheel braking system?).
While researching for this question (How are brakes cooled on heavy aircraft?), I assumed that all of the 20 main wheels are braked. I looked at a few pictures of A380 landing gears. As far as I have seen, all main wheels are equipped with brake cooling fans (BCF), except the four rear wheels in the inner 6-wheeled undercarriages. (e.g. here).
This picture below clearly shows that there is no brake unit inside the rim:
There is another picture here whithout BCFs, but the same four wheels apparently have no brakes.
What is the reason for omitting the brakes at these four wheel positions?
Is this a common configuration, or quite unique to the A380?