When you put a mirror in front of a mirror an infinite virtual image will be created which is an image you cannot touch.
The same image is basically flipped as it would be in a flat/plane mirror and for an infinite number of times while getting smaller each time.
Mirrors facing each other create what's known as an "infinity mirror" effect.
The infinity mirror effect is a series of reflections that appear to go on forever.
It can be super trippy to look at and a cool trick of optics, but it's not a gateway to the netherworld.
When you have two mirrors across from each other, they are streaming energy back and forth between them.
This is definitely something you do not want if they are placed in an area that you sit or sleep between.
This is way too much energy for a relaxing or peaceful space.
If you place two mirrors facing each other in a dark room, legend says you have created a ghost portal through which spirits can pass.