Is packaging module a part of Core?

I saw there are two different files with the same name under lib/ansible/modules/core/packaging/os/apt.py and lib/ansible/modules/packaging/os/apt.py.

Is apt module managed by Core and also 3rd party? This question is from this PR, https://github.com/ansible/ansible/pull/22232#issuecomment-290573934.

Starting with stable-2.3, modules have been moved from lib/ansible/modules/core/ and lib/ansible/modules/extras/ to just lib/ansible/modules/.