C-sharp : Only one of method Equals() and GetHashCode() defined

Only one of the Equals() and GetHashCode() methods is defined in the class.

Equals() and GetHashCode() methods are defined in class Object. Class Object is the root of the class hierarchy. All objects implement the methods of this class. And If you override one of this method, then you should override the other, otherwise, equal (in the sense of Equals()) objects may have different values for GetHashCode().