It's true there were usually pairs of consuls and censors, but there were powerful magistracies that were awarded to individuals, like pontifex maximus and the

It's true there were usually pairs of consuls and censors, but there were powerful magistracies that were awarded to individuals, like pontifex maximus and the tribune of the plebs, the former being a lifetime appointment. Either way, the Republic collapsed into violence, and was hardly blameless in its own fall. Ultimately whatever checks and balances you have, it's very hard to stop power and wealth accumulating, and thus enormous constituencies feeling disenfranchised.