Superset training: same muscle group twice a week?

There are some split programs that hit each muscle twice a week, and there are whole body routines that hit the whole body 3 times a week.

The thing to consider about all these programs is that they adjust the volume of work placed against each muscle for how often those muscles are worked each week and how much time exists between those muscles being worked.

72 hours should be enough time to work chest again IF enough time has passed for both your chest muscles and your nervous system to have recovered from the last workout. If you're 16-24 sets for chest, I think once a week is enough. If you are hitting chest twice, consider one of the following:
1) do only 8-10 sets each time you hit chest
2) do one heavy chest day with compound exercises (barbell press, chest dips, dumbbell presses) and one lighter chest day with isolation exercises (dumbell flys, pec dec). You might also consider doing the dumbbell chest presses on the light day, since you can lift much more weight for mass/strength gains on the heavy day.

Some people have better recovery than others. The supplements you are taking will make a difference too, so if you feel too tired with this program, you should adjust your volume down or decrease your intensity to maintain volume level. Taking each set of an exercise is much more intense than only taking the last set of each exercise to failure.