Main and Slave MB Studio

Hello,
If you purchase second license for slave unit to backup on-air main, do the two mirror exactly what is happening? I wonder how the setup works. I know it has same songs, commercials, settings as the main unit, but what happens when the main fails, crashes, dies, etc.? What is the slave doing at that time the main crashes?

Example:
I have the main on-air playing a song that it picked from random rotation. The slave unit is also running next to it and connected to network and audio goes out to a audio switcher running as the slave.
The main computer fails. I have silence detection, that automatically switches from the main computer to slave computer, so when it fails it would switch audio source from 1 to 2.
Will the slave be playing the same songs, breaks, etc, so if I switch from one to the other they would match and nobody would notice if it was the main or slave switching between the two other than the silence?
Just curious how it works. If not, I know there will be silence 10 seconds and it will switch and some other song will be playing I guess.
Will the play logs be on both computers?
Computer one is on-air playing songs and saving log. Does that same log report show on slave? I assume if both are matching play-out of songs yes, but if they are playing random songs the answer is no?
Wondering how I would do a play report after a crash.

Thank you!