I was wondering the same thing...
I was able to figure out how to stream single videos/songs to multiple computers by typing the following in the "Stream output MRL":
:sout=#duplicate{dst=std{access=rtp,mux=ts,dst=192.168.1.201:1235},dst=std{access=rtp,mux=ts,dst=192.168.1.100:1235}}
(192.168.1.201:1235 and 192.168.1.100:1235 are the two computers I am streaming to)
Now I would just like to be able to do it for playlists if possible
Thanks