Why interface support multiple inheritance whereas classes are not ?

Thats because interface dont ve any implementation. But classes have implementation. So child class dont know to call which implemented method,

Class A
{
void GetDetails()
{
//something
}
}
Class B
{
void GetDetails()
{
//something
}
}

Class C:A,B
{
void secondmethod()
{
}
}
Now if i create object of class C and call obj.GetDetails(), compiler dont know whether to go with class A method or Class B method.

But with interfaces there is no such confusion, because both methods dont ve implementations and only child class will have implementation