Basic Action Super Heroes!

So if a character uses Duplication, he functionally becomes a series of minions. I understand that he only has one attack between all duplicates but could he aid himself in that attack?

No. Not unless you build this as a power or power-stunt it.

For instance I might build a Duplicator that has Special Attack used to represent a whole bunch of duplicates simultaneously attacking someone, or a Burst area special attack that represents the duplicates acting as a mob that damages everything in its area.

Good, that would be incredibly broken.

Agreed.

I should add some nuance to that idea I posited earlier. If you make a duplicator with a gang-up power, you should be sure that it has a limitation <Only> or <Only>, etc.

Follow up question for the hypothetical duplicator, once he becomes a series of minions does he then cease to roll hit/defense/soak, or since he is still a hero/villain would he continue to roll those things?