Double-sided mirrors are cheap 1, and mirrors are different: one side of a double-sided mirror is a mirror, and the other side can see the opposite scene through the mirror. A single-sided mirror is an ordinary mirror, and the other side is opaque.

2. Different knocking sounds: When knocking on the double mirror, the sound you hear is full. When you hit a one-sided mirror, the sound you hear is weak.

3. The discrimination method is different: the finger point of the double mirror is at a distance from the imaging in the mirror. Single-sided mirror with a finger, there is no distance from the imaging in the mirror.