Circuitous - while in an app

You might be better off changing the activation method in Circuitous' settings to something else. Personally when I used it, I had the app switcher appear when I swiped down from the status bar.

You should also check your setting under General > Home and fiddling with the "double-click the Home button for" options until it behaves how you want. Also remember that the double clicking is two quick clicks right after the other, like on a mouse.

But personally I preferred the status bar activation method.