multiple versions of a defaulted special member functions are not allowed (MSVC)

Is this a valid C++ code:

struct S
{
    S(S const&) = default;
    S(S&) = default;
};

?

Context:

I tried to deal with ambiguity in following code by adding these two lines to S (godbolt):

#include <utility>


struct Inner
{
    Inner(int);
};

struct Outer
{
    //Outer(Outer const&) = default;
    //Outer(Outer&) = default;

    template<class T>
    Outer(T&& inner) : inner_(std::forward<T>(inner)) {}

    Inner inner_;
};

auto foo()
{
    auto v1 = Outer(1);
    Outer v2 = v1;
    return v2.inner_;
}

Uncommenting two lines in S makes GCC happy, but MSVC produces error C2580. Question is -- is MSVC correct or not?

The error for the above S is:

<source>(8): error C2580: 'S::S(S &)': multiple versions of a defaulted special member functions are not allowed