How did the Romans ensure that no one person would gain too much power in the Republic?

The Romans would elect two consuls so that one didn't have more power or influence over the other. In a way it was a system of checks and balances. They also limited officials to a term of one year, so that their influence wasn't too much. If they had a need to elect a dictator, they would only allow them to be in charge for 6 months as well.