Why do cinemas or photo studios often use two layers of black and red cloth to shade the light?

Because the light of the camera is mainly red light and black light, black cloth can absorb black light, and red cloth can absorb red light, so the light will not reflect back to take pictures, so you don't need two layers of black cloth to cover it. If the light reflects back, (1) it will hurt your eyes. (2) You can't take pictures.