Maybe somebody else has more info... I have never seen other brake pads than the current ones, but then, they all may have been replaced at some stage. That said, the first Rebour drawing of the Racers, from 1952, which was published in Le Cycle with a note that these wonderful new brakes, carefully designed for maximum mechanical advantage, etc., shows the four-dot pads. If they are not 100% the same, they look very close.
I believe Jan is almost totally correct. The 4-dout pads seems to have remained the same throughout the production. Perhaps they made a rubber compound change but it did maintain the same shape. I do seem to however recall that the cyclo-cross/tandem version did come with a 5- dot pad. Can anybody confirm or deny this?