multiscrobbling is working in mpdscribble as of version 0.18. Set up your
configuration with two server sections such as:
log = ...
musicdir = ...
verbose = ...
url = http://post.audioscrobbler.com
username = <last.fm username here>
password = <last.fm password here>
url = http://turtle.libre.fm
username = <libre.fm username here>
password = <libre.fm password here>