Weathered cut copper and waxed weathered cut copper create one slab in stonecutter instead of two

Summary:

Weathered cut copper creates one slabs in stonecutter instead of two. Also applies to the waxed version. Works only with this stage.

Steps to Reproduce:

1. Place the stone cutter.
2. Take weathered cut copper or waxed weathered cut copper.
3. Try to make slabs out of them.

Observed results:

You can only craft one slab.

Expected results:

You can craft two slabs.

Image: