The access level, signature and the return type can be changed during

When two programming elements share the same name, one of them can hide, or shadow, the other one. In such a situation, the shadowed element is not available for reference; instead, when your code uses the shared name, the Visual Basic compiler resolves it to the shadowing element.

An element can shadow another element in two different ways. The shadowing element can be declared inside a subregion of the region containing the shadowed element, in which case the shadowing is accomplished through scope. Or a deriving class can redefine a member of a base class, in which case the shadowing is done through inheritance.