I fitted an aftermarket Alpine head unit to replace the original (not alpine) Land Rover head unit. The original unit had two plugs on the main harness into the original unit. The Alpine unit has a single plug into the unit. So an adaptor harness is needed, to take the two main harness plugs onto a single plug to go into the unit. Mine looked similar to your pictured harness on the left. If your Alpine unit was factory fitted, I would guess the main harness was already tailored to fit straight onto the unit without an adaptor.