The CH-RCASPLIT RCA splitter is used where two video signals are going to connect to a single monitor or display input.
The separate RCA plugs from the cameras go into the female jacks on the bottom and a single male plug goes into the monitor input but to make this work the power to the camera will need to be controlled so that a single video signal is present at any one time. As RCA camera will have the power wires separate to the video cable the power can be controlled through a SPDT switch or relay so that it is not possible for both cameras to be powered together.