It's pretty hard to find a filter arrangement for a dual output converter, but I came across the following:-
Taken from here.
So for the bottom example, is the LC arrangement correct? I always thought that a -ve voltage flowed into the 0V terminal. That would imply that the lower filter should be the other way around, with the capacitor put adjacent to the converter, and the inductor away from it. That way the current flows firstly though the inductor and then past the capacitor, as it does in the +ve configuration above the 0V rail.
Am I wrong?