Video input sources from computer get transferred to the other computer

I am testing a patch on my home computer. When putting it on my other computer, the video devices stay in the list even if I have not used them there. For example: on my home computer I use a macally webcam, on the exhibition computer a logitech. In the devices menu, I only get to see the macally and not the logitech. Also, I cannot set the compression type. What is wrong? I already deleted the contents of the umenu but it does not change anything