Thank you for your comment. The library catalogue only indicates if a book is available to borrow. Should someone want to use a book while they are in the LRC the book will remain "Available" on the catalogue. This is unfortunate but understandable.
I would always advise checking the shelves near where the book is supposed to be and check the "Collection Points" where books are stored prior to be being re-shelved. I am sorry but having reference copies behind the counter, of all our books is just impractical and would never resolve the scenario of where the Reference copy is already being used.