While tuning around the shortwave dial as the sun went down I came across a clear signal that happened to be a religious program describing their various satellite channels that I guess were used to distribute their programs.
The preacher explained that they were sending two different programs over a stereo-pair of satellite channels, with one (mono) program on the left audio channel and a second (mono) program on the right audio channel.
So I got to wondering if that could be done with FM stereo...
Obviously on a mono portable receiver you'd hear both audio programs mixed together, but on a stereo receiver you could turn off the right speaker to hear the mono program on the left channel and vice versa.
What could go wrong with that?