With helos, lifting external cargo isn't quite as straightforward as the weight, though - yes, the Chinook can lift itself but they have to do things like remove the rotors (to prevent weird lift effects, and strain on the brake that's trying to stop the blades autorotating as you fly). The loads have to follow certain rules of aerodynamics, both for flight and for not disrupting the rotor downwash.
So yes, we could Chinook a Chinook into an area... but unless you want to spend a day or two reassembling it all it's probably not worth it