Diversion / hidden safes mostly all have hidden compartments and look like the real thing because they usually are. The key to successfully positioning your secret safe / hidden safe is to make sure you place it where it belongs.
This is where the hidden safe excels over most other safes. It's more likely that intruders will look in drawers and under your bed to find your valuables as quickly as possible, then leave as quickly as possible.
So, if you follow the golden rules and keep your secret safe where it would normally belong, then the chances are it will never be detected by anybody.