As Tobias said, their not quite ready for the funny farm in Stuttgart.
In the mid sixties, "dual master cylinders" became a new safety feature in all cars. By having seperate cylinders,(actually two in line cylinders and pistons) and two reservoirs, a leak in one, does not render the other useless.
If you only had one reservoir, a leak anywhere in the system would lose your fluid and eventually ALL your braking.
The way that the Benz reservoir is arranged, it's not as obvious that there are actually two reservoirs. On many American cars it is more obvious.
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in