Powering up the 2nd voice coil with another Nuforce amplifier is not a problem. This is quite different from the issue with an active subwoofer amp taking speaker level input.
However, if you plan to use a signle Nuforce amp driving both voice coil, please be careful and start slow, the halving of load impedance from the parallel connection will draw twice the current and could melt the voice coil if they are not designed to handle the power.
However, if you plan to use a signle Nuforce amp driving both voice coil, please be careful and start slow, the halving of load impedance from the parallel connection will draw twice the current and could melt the voice coil if they are not designed to handle the power.