Found this on multiple vanguard cams... You may have seen this already
Question
How can I hook up and control multiple wired Vanguard cameras?
Answer
You will need a quad processor or multiplexer; you can order a 4-cam color unit for $210 by calling 800-675-3044. Hook all your Vanguard cameras into your multiplexer using the RCA video cables, directly from the wired output on each Vanguard camera. Set each Vanguard to TRANSMIT ENABLE (yes, this does not seem logical, but do so anyhow.)
Each camera comes pre-programmed as camera 1 (C1). The first camera you set up will stay C1. Program the additional cameras as C2, C3, and C4:
Pick the camera to use as C2.
Set the mode switch on the bottom of that camera to Program.
Press C2 on your remote control to set this camera to C2.
Set the mode switch back to Transmit Enable.
Repeat these steps for the rest of the cameras, using C3 for the third camera and C4 for the fourth camera.
When you turn on your TV/computer, you should now see all four cameras live on the screen at once. When you press a C1, C2, C3, or C4 button on the remote, the remote should control that camera exclusively.
Retrieved from "
http://kbase.x10.com/wiki/Multiple_Wired_Vanguard_Cameras"
So it looks like X10 is saying the only way to get multiple Vanguard cams is to use a Video Processor.