birch half slabs

When you place birch half slabs on the top half of a block, the sometimes change into jungle half slabs.

What I expected to happen was...:
a birch half slab to be placed on the top half of the block

What actually happened was...:
hey jungle half slabs placed on the top of the block

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
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