This multi-camera adapter board is designed for Raspberry pi ZERO and let you connect two 5MP or 8MP cameras to Pi Zero.
Only one of the two cameras can be activated at a time, and they are working in alternate ways. It cannot run two cameras at the same time, but we build a simple software which can run two cameras and make it looks like working at the same time.
But the drawback is the frame rate, and resolution will be fairly low, may be useful for surveillance.
Please note that Raspberry Pi multi-camera adapter board is a nascent product that may have some stability issues and limitations because of the cable’s signal integrity and RPi's closed source video core libraries, so use it on your own risk. This version supports 8MP Pi camera board. And it also can be used for other Raspberry Pi boards with minor software modifications.