There are ways to utilize either a mono or dual mono track in multiple ways.
Most home theater systems have either a "dual mono" setting and/or a"mono film" setting that can be used to spread the mono audio track between 2, 5.1, or even 7.1 speakers, instead of just the center channel.
If you use a dual mono track and play it with dolby pro-logic enabled it should send all the audio to the center channel. This gets you back to the mono only setting, if desired.