Why do you need it filtered?
I don't really but I may want to plug a phone in occasionally. What I'd like to do is plug a modem/router into the wall socket, directly without a dangly filter. I can't use the phone socket as its the wrong type so I thought a faceplate with a filter would be the best way.
Just take two pairs, filtered and non-filtered to the second location. You have Cat5e so four pair available.
Clever... Where's my filter? To be honest I've currently removed the master socket filtered faceplate and am using the standard OR plate (no phone connected). I'll have to dig it out and see if it has a method of 'extending' the filtered output. And then I'll need a double socket extension faceplate.