Disenchanted books does not stack with normal books

What I expected to happen was...:
That the book i removed the enchantment from via the grindstone would stack like normal books

What actually happened was...:
After disenchantment i have a set of books which cannot be stacked with normal crafted books. 

Steps to Reproduce:

1. Craft 2 books 
1. Enchant 1 book
2. Remove enchantment using grindstone
3. now the 2 books cannot stack