I struggled with the redefinition problem. I want to write a class UniFraction like this.

template<typename Type>
    class UniFraction {
    private:
        unsigned int id_;
        Type numerator_;
        Type denominator_;
    public:
        
        // some code     
          
        friend UniFraction<Type> operator+(UniFraction<Type> &first, UniFraction<Type> &second) {
            // implementation for simple types
        }

        friend UniFraction<Polynomial> operator+(UniFraction<Polynomial> &first, UniFraction<Polynomial> &second) {
            // implementation for polynomial fraction
        }
}