Any single video output going to two monitors will be supplying the same horizonal/vertical refresh and the same resolution. Devices such as you mention will provide some isolation and signal attenuation but I don't see that to solve a problem where two different signals might be necessary. You can run separate video cards or find one with multiple outputs that might suit you better. Hope that helps but I cannot answer your question directly.
I would like to split the monitor signal from the computer (15 pin SVGA), with one going to a monitor that is hooked into a KVM switch, the other to an LCD t.v., which has a monitor capable input.
I initially tried this with a monitor Y cable, but the monitor behaved erratically, as if it wanted to turn on and off. The LCD t.v. looked normal, except it flashed some signal "over size" which I haven't yet investigated.
Would a video distribution amplifier, for a 15 pin monitor cable be available for sale? One input, with two outputs? I assume this would solve it.