Books are like my friends and provide much comfort, entertainment, ideas. I've never counted my quilting books. I have arranged and rearranged several times; by subject; by author; by size; my favorite ones. Looking at my collection, someone would think I am a very talented quilter. Like you, I did find duplicates. I bought one book three times. I thought there was something wrong with me. Of course, I read books and watch movies over and over as well. Then books find there way to in my bed, under my bed, sofa..every where. I need to do a Excel workbook also. (Magazines are also organized by particular magazine, then by dates but I don't like this arrangement either.)
When I go to the library and check out quilting books, the checker always says something about making these quilts. I have to laugh and say No, I just look at all the pictures and dream.