[BUG]: "Already defined" import error when reusing a value name in different enums

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What version (or hash if on master) of pybind11 are you using?

v3.0.3

Problem description

native_enum value names seem to have global collision scope. When adding a value with a name which was already used in another enum, it compiles successfully, but an ImportError is raised when importing.

Reproducible example code

#include <pybind11/pybind11.h>
#include <pybind11/native_enum.h>

namespace py = pybind11;

enum class SomeEnum { value, another_value };  
enum class AnotherEnum { first_value, second_value, another_value };

PYBIND11_MODULE(enum_collision_test, mod) {

    py::native_enum<SomeEnum>(mod, "SomeEnum", "enum.Enum")
        .value("VALUE", SomeEnum::value)
        // First definition which uses "ANOTHER_VALUE"
        .value("ANOTHER_VALUE", SomeEnum::another_value)
        .export_values()
        .finalize();

    py::native_enum<AnotherEnum>(mod, "AnotherEnum", "enum.Enum")
        .value("FIRST_VALUE", AnotherEnum::first_value)
        .value("SECOND_VALUE", AnotherEnum::second_value)
        // Causes ImportError: pybind11::native_enum<...>("AnotherEnum").value("ANOTHER_VALUE"): an object with that name is already defined
        .value("ANOTHER_VALUE", AnotherEnum::another_value)
        .export_values()
        .finalize();
}

Is this a regression? Put the last known working version here if it is.

Not a regression

Start with the native_enum usage in the reproducible C++ example and trace how value names are registered during finalize(). Verify the behavior with two enums that reuse ANOTHER_VALUE, then add coverage for the expected import behavior. Done means distinct enums can reuse a value name without an ImportError.