c++模板的定制问题

#include<iostream>


template<class T1,class T2>
class Mytemplate
{
    private:
       T1 obj1;
       T2 obj2;
    public:
        Mytemplate(T1 o1,T2 o2):obj1(o1),obj2(o2){}
        void display()
        {
            std::cout<<"object display:"<<std::endl;
            std::cout<<"----------------"<<std::endl;
            std::cout<<"object 1: "<<obj1<<std::endl;
            std::cout<<"object 2: "<<obj2<<std::endl;
            std::cout<<std::endl;
        }
};

template<class T1>
class Mytemplate<T1,char>
{
    private:
        T1 obj1,obj2;
    public:
        Mytemplate(T1 o1,char c):obj1(o1),obj2(o1)
        {
            obj2+=(int)c;
        }
    void display()
        {
            std::cout<<"object display:"<<std::endl;
            std::cout<<"----------------"<<std::endl;
            std::cout<<"object 1: "<<obj1<<std::endl;
            std::cout<<"object 2: "<<obj2<<std::endl;
            std::cout<<std::endl;
        }
};

int main()
{
    Mytemplate<int,int> mt1(10,20);
    Mytemplate<int,char> mt2(10,'b');
    mt1.display();
    mt2.display();
    return 0;
}


d:\source\c++\标准c++\pr15010\aaa.cpp(40) : error C2989: 'Mytemplate<T1,char>' : template class has already been defined as a non-template class
d:\source\c++\标准c++\pr15010\aaa.cpp(40) : error C2988: unrecognizable template declaration/definition
Error executing cl.exe.
 
谁知道是怎么回事啊？？？！