There has been little conversation or consideration of implementing a "dual server" master/slave, main/backup configurations, or more strategically a small cluster environment.
Are you sure of that?
I dare you to search for "server cluster" in this forum using the excellent search functionality Moodle.org has. Or to search for "Moodle server cluster" on Google. Open challenge. Hit that Search button with force... and please post the 'top picks' of what you find.
Edit: removed 2-server comments -- I was obviously misreading. And the correct strings to search for would be "Moodle High Availability HA". Which gives great hits on Google too