MVS Hulking Memory/headphone Cables

A question I've long wondered, why dose the external memory card/headphone board require 2 50pin cables for the memory card alone since the audio comes from the separate 4 pin cable? Was there possibly additional UI boards planed like a double card one?

The two 60 pin cables are for player 1/player 2 memory card read. Single reader but two seperate connects from the MV-1C to the motherboard, one for each player.
The headphones are connected via a standard 4 pin hook up.