Yes, you can watch all your cameras simultaneously in
WebCam Monitor.
Add all your cameras. Right click on camera preview and select Detach camera from the Context Menu.
Move the detached camera window to the desired position. You can also re-size the camera window. Next, right click on the detached camera window and select the 'Always on top' option.
Repeat the same steps for the other cameras. When you are finished, you will be able to view all your webcams simultaneously on the screen.