I brought several lots of Zigbee contact sensors and installed them using ZHA and the official HA blue Zigbee USB dongle.
The devices were basic white label rebrands. Some of them have two attributes labelled as “opening”, or they have “Opening” and “Opening 2”.
The first one does exactly what you would expect, it’s just a regular Open\close binary state that triggers when the sensor contact is broken and records in the history tab.
The second is always closed, even when the contact is broken, and it has nothing in the history. I’m not able to find any evidence that it does anything in HA.
I know that people get a little funny about white label sensors, but there doesn’t seem to be much of any use in identifying it any further.
Sometimes a sensor can go both ways meaning that the it can detect a magnet on each side.
This makes it possible to have it detct both the door being in the closed and open position with the same sensor.
l’ve just checked that and it looks like mine will only detect on both sides if you flip the magnet over, so it’s probably just one sensor being pushed or pulled rather than two sensors.