Before Travel Agents and Shiftmates, there were similar devices with a single pulley, which were intended to give easier gear changing by replacing the tight loop of cable outer by the rear mech with a relatively straight section, plus the pulley, and it looks like the OP's photo is one of these.
The name escapes me for the time being.
They never really caught on, so either any improvement was minimal, or it was offset by problems caused by the pulley device.
