duplicate entries with "subdatabase on .aux file" tool and crossreferences

[ghost]

version JabRef 3.8.1 on Debian stretch (2017-01-20)

When using the tool "create subdatabase on .aux file" with a reference database.bib using crossrefrences, the generated subdatabase has duplicate entries for the crossreferenced entries. Then bibtex makes error with the generated subdatabse due to the duplicate entries

Steps to reproduce (1 create aux file from tex and then use jabref on .aux file). Filenames are jabref.tex and ref.bib

1. jabref.tex

    \documentclass[letterpaper, 10pt]{article}
    \usepackage[authoryear]{natbib}
    \usepackage{lipsum}
    \begin{document}
    \lipsum[1-4]
    \cite{Lastname1xxxxa,Lastname2xxxxa,Lastnamexxxxa}
    \bibliographystyle{apalike}
    \bibliography{ref}
    \end{document} 

2. ref.bib (3 entries)

    @InCollection{Lastname1xxxxa,
      author    = {Lastname1, Firstname},
      title     = {Title},
      year      = {xxxx},
      volume    = {xx},
      number    = {xx},
      pages     = {x--xx},
      crossref  = {Lastnamexxxxa},
    }
    
    @InCollection{Lastname2xxxxa,
      author    = {Lastname2, Firstname},
      title     = {Title},
      year      = {xxxx},
      volume    = {xx},
      number    = {xx},
      pages     = {x--xx},
      crossref  = {Lastnamexxxxa},
   }
    
    @Book{Lastnamexxxxa,
      title  = {Title},
      year   = {xxxx},
      editor = {Lastname, Firstname},
      volume = {xx},
      number = {xx},
    }
    
    @Comment{jabref-meta: databaseType:bibtex;}

3. Makefile

    jabref:
	pdflatex jabref.tex; bibtex jabref.aux; pdflatex jabref.tex
	jabref --nogui --aux jabref,ref-generated.bib ref.bib

4. ref-generated.bib output (now with 4 entries, aka one duplicate)

@InCollection{Lastname2xxxxa,
  author    = {Lastname2, Firstname},
  title     = {Title},
  year      = {xxxx},
  volume    = {xx},
  number    = {xx},
  pages     = {x--xx},
  crossref  = {Lastnamexxxxa},
  owner     = {Néhémie Strupler},
  timestamp = {2017.01.20},
}

@InCollection{Lastname1xxxxa,
  author    = {Lastname1, Firstname},
  title     = {Title},
  year      = {xxxx},
  volume    = {xx},
  number    = {xx},
  pages     = {x--xx},
  crossref  = {Lastnamexxxxa},
  owner     = {Néhémie Strupler},
  timestamp = {2017.01.20},
}

@Book{Lastnamexxxxa,
  title  = {Title},
  year   = {xxxx},
  editor = {Lastname, Firstname},
  volume = {xx},
  number = {xx},
}

@Book{Lastnamexxxxa,
  title  = {Title},
  year   = {xxxx},
  editor = {Lastname, Firstname},
  volume = {xx},
  number = {xx},
}

@Comment{jabref-meta: databaseType:biblatex;}

->The entry @book is now duplicated. Of course you could clean the subdatabase but this bug wasn't present in earlier version. Sadly I am not sure when it appeared but I think that this bug wasn't present in the version 3.4. I can't say when it appeared exactly and if it is related (only) to 3.8...

Thanks for your great work, and I am sorry that I can't help further

[lenhard]

Hi @Nehemie

Thanks for your report. I wish all users would provide a minimal working example, as you did :)

I can confirm the error and implemented a fix. A working version is available at http://builds.jabref.org/fix-aux-duplicates/ Just to be sure, could you please install this version and check that it fixes your issue?

As a side note: I think in BibTeX it is mandatory that entries which are being crossref'd have to appear in the file before the entries which reference them. Resorting the entries has no effect on the issue described here, though.

Regards
Jörg