Two interface have same method in C#

Interface I1
    {
        void fun();
        int fun1();
    }
Interface I2
    {
        void fun();
         string fun1();
    }
 class temp : I1, I2
    {
        void fun(){ ......}  // No compile error because two method has same signature,
                                    //Run Time is throw error.
        int fun1(){......}  // Error: we have explicit declare both methods
     }