Explanation: The bust pictured is of the Emperor Diocletian, a later Roman Emperor who decided that one Emperor just wasn't enough. In fact, he decided two Emperors wasn't enough, and neither was three - for the first time in the Roman Empire's history, it had four (theoretically) legitimate Emperors ruling over the place - two senior Emperors, and two junior Emperors - the Tetrarchy.
It uh, did not work well once Diocletian retired to farm cabbages (no joke, literally what he did). It can even be argued that he outlived the system. Turns out, four Emperors IS a lot!