When you make double slabs (with slabs that are affected), they will turn into weird glitched blocks.
Red Sandstone Slab
Prismarine Bricks Slab
Dark Prismarine Slab
Watch -> https://streamable.com/nrz2o
Dubble slab forms a block
Unable to stack slabs upon switching worlds
When making double slabs, block IDs are ignored, allowing stone_slab to combine with stone_slab2