Carter Duck, is as close to the original Dave Loo Duck as you get. The Carter does not have an insert barrel or barrel kit leaving you with a huge bore. You can get an in handle slam changer for it.
The Redux is more like the Duck 2.0. Phantom guts, a lot of look and feel of a Carter but costs less. Also has a Freak insert bored barrel.
Both come standard with inhandle changers.