#392 keep bibtexkey unique in all *.bib files

[pem]

when using several *.bib files simultaneously, the keys generated in differernt files may conflict.

For example,
record A in A.bib:
G. Manya and ...,2000
record B in B.bib:

S. Manya and ...,2000

they will have the same key, Manya2000, if have them generated automatically. This may cause problems when A.bib and B.bib are used simultaneously in a article.

Better if there is a option to keep bibtexkeys unique among all *.bib files.

Many Thanks.