Strange additional pulley on harmonic balancer, crankshaft

First post for me. I'm installing full Retro Air AC kit, new condenser fans and doing timing belts on my '84 308QV Euro. Another member noted I have an unused pulley outside of the normal crankshaft pulleys. Anybody know what this pulley drives? Can I, should I remove it? I will have the working fans, York-style compressor, condenser, dryer, etc. available to someone in need. I was able to remove my gas tank with the old compressor and cam belt covers off w/o removing anything else such as suspension parts or the rotor.
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