Duplicate books on reader
Please help!! I get how to add books to the Calibre library and put them on my reader (Sony PRS505) What I don't get is how to sort through books in my library that are already on my reader so I don't add them a second time when adding new books to the library/reader.
Say I have 10 books in my library already and those 10 in my reader also..now I add 5 books to my library (15 total) How do I only add the 5 new books to the reader? If my library is large there is no way I can sort through them all for duplicates.
Hope someone can help me please.