Many screen "iPhone" capture at the same time

God Morning!
For me its not enough to use the “mobile app” for linking my two iPhones (which i use as webcam) because despite having good bandwidth (120Mbs) the video its not continuous and the quality its not good.
Its so much better using a USB cable to capture my iPhone screens. But…
… my difficulty is that ManyCam does not allow to connect two (or more) screen captures at the same time, its looks like only accept one at a time.
Or maybe I don’t know how to do it…
Can someone help me?

Pd: the application for the smartphone should run also with USB cable not only by WIFI.