That is what deep basement storage is for.
A last copy policy will ensure that when one wants to compare a first edition of _The Fellowship of the Ring_ against a second, one can get the full weight of Aragorn's snark:
>What did you fear that I should say? That I have here a rascal of a rebel dwarf that I would gladly exchange for a serviceable orc?'
That is what big national central libraries are for. Hopefully government funded libraries actually properly archiving everything printed in the country.
This is a brilliant observation, in regards to the first edition's depiction of Gollum.
In the first edition, he was depicted as a large creature, and Tolkien was upset about it, and in the second edition, changed the description to small.
This information was gathered by a rare book seller who's videos I find immensely interesting.
Schools in poor towns don't have multiple levels or basements or even extra storage rooms. What you see is all you get.
If there is enough space to have a room full of books, it would be better used as a publicly accessible set of stacks. The only real reason to have a librarian-only room is for books that are rare and valuable.