Apparently, when there's 2, or more enemies on the screen it's possible to wipe them all out using Twin Flare's combined powers. Though, the twins need to deal the final blow, and the secondary enemies cannot be damaged for the glitch to work. I've tested this a few times, and it seems to work on just about every enemy. Pink Puffs, Red/Blue Dragons, Minds, Breaths, etc.
If you need me to show you, just ask me in game and I'll show you first hand.