I figured out the problem with LED Screens. The problem was the LED Bodies and the LED Modules in Z-fighting (same plane). I imported my stage made in Vectorworks into another software and the same problem with the stains happened too.   So in debate with other users , I realized that if I moved the frontal plane 1mm away from the cabins (modules) the problem would stop happening. So in Vectorworks, I went to the LED Screen classes, and tried the various options. S