So this is the sequence of events on my Mac
- initiate Calibre
- Initiate Chrome - Chrome set to auto open epub files
- Download an epub file using Chrome -> Calibre adds the file correctly to the library
- Download another epub file -> Screen shows something happened, book is not loaded. Cannot be found when looking at the book files under the author
- Drag the file into Calibre -> Calibre says file already exists- Click ok, file is loaded and only one copy exists