What is actually written
A current drop, remove, or destroy step is not verified from the saved official text. The bag card also does not specify active-book selection or overwrite behavior.
The Grimoire Bag allows up to 2 copies of each grimoire. The base price is 450 Robux with regional pricing enabled. This does not imply a two-book total limit, one equipped plus one stored, or a particular inventory-management workflow.
What to do if the book is the wrong one
The tower lists available books, but its current text does not establish how a new result interacts with an existing book. Do not assume a roll deletes, replaces, or frees a slot. The verified bag capacity is on its own page; it is not a documented delete mechanism.