a book bug in 1.2o snapshot

Hello mojang i saw a video that shows a bug in a snapshot for 1.20 its the 12th type in this video https://www.youtube.com/watch?v=eb-GC0N6TJo [the 3th min]
the bug is about duplicating books in the new bookshelf, when you fill the bookshelf and start clicking with another book it will duplicate. and u will get how much you want from the book[enchanted books].If someone else tipe you about that I'm sorry for disturbing you.