Using a voice assistant (like Google assistant), these understand how to treat plurals, so if you use the same base name numbered 1 & 2 you can say: turn on the (base name) lights and both come on without having to try to define scenes or explicit device groups or links. They can still be controlled independently, so I number in a sequence relative distance to the 'entrance' to that room, or left to right, you might want clockwise.
I use names related to the room, area or object, like: entrance light, dining table light, craft area light, fan light, hallway light, tv light, desk light, bed light, reading light, kitchen sink light. Numbered 1 & 2 if needed since usually want them on together.
Or may be further refined by type like: night light, down light, spot light, string light, stand light, lamp, bulb, LED etc.
Hope that helps with a few ideas?
Suggest the typical hardware device troubleshooting. watch/tail your dmesg -w or kernel log as you add the extra drive. It's curious that the system itself doesn't crash, but from your description it still sounds like a power starvation concern or possibly high temperatures if this device is under heavy load.