I am using two webcams and connected a secondary display to laptop for the exam. when I did a compatibility check one cam is passed 2nd cam showed only a black screen. so it is not possible to run two external webcam simultaneously in exam connected to laptop. We have to use one laptop inbuilt cam and one external webcam.
Only one external camera is required for the exam.
There is no need to connect a second external camera or use the laptop camera if you use the external monitor instead of the laptop monitor