How was the front mirror shot taken in the movie?

The characters in the film look at themselves in the mirror. In fact, at this moment, the characters see not themselves, but the photographer. But the photographer takes the image of the front of the character. The mirror is not pointed at the characters and photographers. People and photographers face the mirror at the same angle. You can find a partner to look in the mirror with. You see him, and he will see you. The mirror is not pointed at you and your partner. When you see him, it is his positive image, just like the effect of the film itself in the mirror. It's the same for your companions to see you.