/// # Safety
///
/// If any other `Rc` or [`Weak`] pointers to the same allocation exist, then
- /// they must be must not be dereferenced or have active borrows for the duration
+ /// they must not be dereferenced or have active borrows for the duration
/// of the returned borrow, and their inner type must be exactly the same as the
/// inner type of this Rc (including lifetimes). This is trivially the case if no
/// such pointers exist, for example immediately after `Rc::new`.