As sibling notes, it is. It's very rarely seen though.
One place you might see something like it is if an API takes ownership, but returns it on error; you see the error side carry the resource you gave it, so you could try again.
That's true of mutable references too though isn't it? In fact lots of people have suggested they should really have been called "exclusive references", since you can actually mutate some objects through non-exclusive references (called "interior mutability" normally).
