Starting from API version 61.0 and later, private methods are no longer overridden by an instance method with the same signature in a subclass. This change is versioned, so to prevent the override, update your abstract or virtual classes that contain private methods to API version 61.0 or later.
Previously: In API version 60.0 and earlier, if a subclass declares an instance method with the same signature as a private method in one of its superclasses, the private method is overridden by the method in the subclass.