Merging metadata when adding duplicate
Is there a way to merge books metadata when adding duplicate book ?
I want to import books that have covers, summary, rating, publishing date in the records, but not series/serie_index. Many of those books aready exist in my lib, but with no covers, summary ... but they have series/serie_index set.
I would like calibre to keep covers,summary ... from the new import even in case of adding new format to existing book.
Is that possible ?
As a side question, Is at possible to launch 2 instances of calibre pointing to 2 different libraries ?