Font book: duplicates are not actually duplicates
this is based on bitmap fonts (OTB) which in the past where optimised for a certain font size. This is not a font family. Therefore the Font ID - which is used by Fontbook to identify fonts - of each of them is the same.
You could use e.g. FontForge to change the ID, but for a variety of reasons I wouldn’t recommend that. Why not use a vectorbased, monospaced font? There are lots available for free including bitmap-like looking  ones e.g. here, here or here.