I have merged a Calibre ebook library and have many duplicate books. In total there are approx 32,000 books. Most are duplicates (I appear to have between two and five dupes for each book). I would like the duplicates merged so the formats (mobi, epub, pdf, etc.) are all contained within one record.
For example, on a Mac one would hit "option+caps lock+M" to combine. On a PC there is a similar command (I think it might be alt+shift+M).
Optionally, I would also like meta-data downloaded for each book (once books are merged).