How are you editing the lamp? If you’re using the checkbox in the Inspector, it should only apply to that specific node. However, if you’re changing the value in the script itself, it will apply to all instances of the scene.
Ah, I see you’re using a material. I believe the material resource is shared among all instances of the node. If you expand the material and choose “Local to Scene” it should start applying to that scene/node only.
So first in the main level scene where i put all my lamps i must select them and, in the inspector, select “Make Sub-Ressources Unique”.
Then, like GBWD said, in the scene of the lamp, go to “Resource” and ckeck “Local to scene” property of everything that need to be individual (meshs, materials, etc.)
I find the process pretty tedious (here it’s only 2 lamps but i will get tens of them per level so…)