I don't know what it means, but I might know what it's used for:
If those connections are spliced into the normal R and L audio wires via a short loop, it's for certain boards that require to you remove a jumper in order to connect front panel audio.
On those boards, removing the jumper disables rear audio and gives you a place to connect front audio. They do this so you won't overload the sound system by connecting 2 devices.
Having a loop back serves the function of the jumper AND allows a front panel connection. Having both means that you should either unhook or turn off any speakers connected to the rear panel when using the front panel.
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