With the Maggie's General Fitness protocol (2 hrs of calisthenics, 2 hrs of HIIT and endurance cardio, and 2 hrs of difficult weights), there is no need to do any single exercise twice in a week.
Some examples:
For legs etc, you can do deadlift one day, barbell squats another. Or leg-press.
For HIIT, you can do stairmaster one day, treadmill sprints on another.
For triceps, you can do press-downs one day, skullcrushers on another.
For calisthenics, the list of choices is so long that you always vary what you do.
Varying the things you do reduces boredom, but also keeps your neuromuscular system nimble and adjusting.