Why does my subwoofer have dual connection terminals?

If your subwoofer has a 4-pole connection terminal / double connection terminal, this is due to the subwoofer chassis installed in it (double voice coil driver). You can now drive the subwoofer with a powerful 2-channel power amplifier or a cable bridge is needed to drive a monoblock amplifier. Study the connection diagram of your subwoofer, pay attention to the correct impedance! You will find a connection diagram in the manual of your subwoofer.