Why does the built module name end with ".so.so"

[ltyylt]

Hi, I just started trying this library. I'm not sure if I've encountered a real issue on Mac and Linux. when I build with CMake, the produced module is named with the suffix .so.so. To proceed I have to add set(CMAKE_SHARED_MODULE_SUFFIX "").
Is this intended behavior? I tried pybind11 with the same setup and did not encounter this issue.

CMake version : 4.0.3
OS : Mac OS & Archlinux
Compiler : Clang17, clang21, gcc 15.1

code:

#include <nanobind/nanobind.h>

int add(int a, int b) { return a + b; }

NB_MODULE(my_ext, m) {
    m.def("add", &add);
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.19)
set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)
find_package(Python 3.8 COMPONENTS Interpreter Development.Module REQUIRED)
project(my_ext LANGUAGES C CXX)

# set(CMAKE_SHARED_MODULE_SUFFIX "") # I must have this to remove one duplicated .so

add_subdirectory(3rdparty/nanobind)

nanobind_add_module(${PROJECT_NAME} main.cpp)