Two instances needed for CPU+GPU usage?

[gabrielseibel1]

Say one has a mining rig with a performant CPU and GPUs. With the example mm.json on README.md, the computer would only use either the CPU or the GPUs at a given time, correct?

Would a good solution to that be: having two mm.js instances (with different ports), one for CPU miners, one for GPU miners?
Is this needed / recommended?

Thanks