Copying written books creates 0-stacks/duplicates original

When copying written books, the original written book's stack size doesn't stay unaltered (like it should when you're copying). Instead, first it subtracts one from the stack size, then it doubles the stack size in a failed attempt at restoring the original stack size. Apart from the hacky way this is implemented, there are multiple problems arising from this:

• If you only put in one original book, the count will go down to 0
• If you put in more than one original book, the count will increase (*2-2 is applied)