You could use any audio or av 2 input selector and split the output. Doesn't matter if the other output gets the signal too? You could build one with 2 outputs.
by just putting another set of outputs in parallel.
I have decided to build a variant on the article from http/www.instructables.com/id/Dual-Input-Audio-Switching-Circuit. I have bought the components for having two switches - One to change the input and one to change the output. Hopefully it works.