Using a camera output on an other camera's mask texture

Hi

I have a project in which I want to use two cameras. One of them is a normal AR face camera where a mask appears on your face. The other is pointing down at an image on a paper and its output is used as the texture of the first camera’s mask.

However I don’t understand how to have two cameras running at the same time. I thought about using two instances of DeepAR but I don’t know how to make them communicate with one another while running at the same time. Can I connect the two cameras to a single instance ? Can I get the output of the second camera with a script ? If you have any idea I would be grateful of any help.

Thank you in avance