No I realize you can add physical books to calibre but at a minimum you would need a custom field indicating its a physical book so you could have a virtual library you could display them in and search on. mixing it up with digital would be a bear if all i want to look for was paper. However with reader ware and a scanner it has a scanner add books function that you can scan a batch and then add them and as part of the adding double check they are adding correctly or select ones that didn't work correctly and pull them as part of the process to do over or manually over ride. I did thousands of books. if I had had to do them one at a time I would have just quit.
I'm pretty sure I could save the isbns that been scanned into readerware and import them into calibre.. except there are more than a handful that the isbns are bad or don't exist at all.
calibre is for me way more about reading the metadata of the digital files and importing stuff in. Batch imports in calibre generally has massive amounts of errors in the import process with no ability to validate them before they are added to the database. So you then have to go back and look through everything and edit it to fix errors.
Readerware is designed literally as a library management system with built in checks and balances for non standard add in books and batch adding of physical books. It is a much slower process even with batch scanning books in but it forces you to validate as part of that import process. There are a lot of literal real world libraries that readerware is their full managements system for books and customers/clients. Totally different customer base than calibre with a totally different design philosophy. Functionally there is a huge amount of overlap and because at the base of it they are both databases with the ability to create custom fields and such you could warp either of them toward the functionality of the other for some stuff, but not for all of it.
calibre has device import/export features for books. As well as importing of books and automatically adding them to the underlying filesystem. Readerware has check in and check out functionality. Calibre had built in ereader and editor. Readerware does not. You could add digital works to readearware with links to a specific file on the file system but its at least in the version im using a manual operation. I'm one behind so no telling if they have added more digital functionality in. It would be awesome if you could merge all the features of both into one program but kovid would kill us
lol. I'm pretty sure you build in a lot of the functionality into calibre through plugins. Just someone would have to be capable and willing.
Though..... im not sure plugins would work for at all for multi user client/server features. That is backend database design to allow for locking and editing by multiple people simultaneously.
Though you could say the content server at least for read only operations gives full multiuser functionality.