deepslate_ore generates with ore in deep ground

deepslate_ores generates with  common ores when they are wrapped by deepslates.

What I expected to happen was...:
there are only deepslate_ores when they are wrapped with deepslate.

What actually happened was...:
deeplate_ores generate with common ores in deep ground, even below y=-30.

Steps to Reproduce:
Just generate deepslate_ores in deep ground.