Have you renamed them to “library” and “data”? I think you need to remove or rename the existing “library.db” and “data.db” files and rename your backups to “library.db” and “data.db” (the extension is important).
I don’t use Windows so I suppose there may be some Windows gotchas I’m not aware of.
You probably have Windows set to hide known file extensions so your existing files (for example “library” with a type of “Data Base File”) actually have a .db extension that isn’t shown in Windows explorer.