Is it possible to add multiple files of the same format to a book in the Caliber library?

Question

Electronic books

Let's say I have a book in all major formats, but for example in PDF format I have two versions of this book that I want to keep. It doesn't matter for what, there are different reasons for that and there are a lot of such books ..
How can I do this, since I cannot do this in a standard way. When adding a second file of the same format, it replaces the one already there.