DLL symbol identity

[Kagamin via Digitalmars-d]

bool checkIfSomeClass(Object o)
{
   return typeid(o) is typeid(SomeClass);
}

Doesn't typeid(o) extract TypeInfo from the object? If it's 
stored as a physical value in the object, how can it change 
transparently for const class?

As I understand, C++ resorts to preinstantiation of needed 
templates when compiling to dlls.