I had seen the paragraph in the manual about importing libraries where it talks about choosing libraries and locations:
https://manual.calibre-ebook.com/faq...ter-to-another
But was still worried about it overwriting things. However, after going through it on the laptop, there wouldn't have been a problem. After accepting the warning dialog, it pops up another dialog about the libraries available to import and asks where it should put them. I only had to import the small library where this book was and I could have put it anywhere. So, I would have been fine doing this on my main machine.