automatically safe the bibfile backup

Thanks for BibDesk!
I have a problem with the "Automatically save a backup document every x minutes" feature. Suppose I have 'test.bib' open. Where is the automatic backup stored? I would prefer it were 'test.bib' itself for the following reason: I run BibDesk on two computers and sync the papers and bib-file via 'unison'. If I forget to explicitly safe the bib-file (at the end of a working day) on one machine it gets not synchronized to the other (at home). However, if the auto-backup feature would write to 'test.bib' it would. Is the problem clear?

My suggestion would be to store the bib-file 'test.bib' itself every x minutes.
Any suggestions?