Thank you very much for your answer. This helps me a lot
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So basicaly, if I import .pdb files, it is better to convert them to another format an open the new one (for example mobi). And the only way how to back up the books in correct folders and with correct filenames based on the metadata is to use the save to disk function of Calibre? If I backup the Calibre library folder, I will still have the wrong names which were created while importing books...
Thanks again, now I can start with importing and moving books to Kindle
