[Koha-devel] Orphaned biblioitems

[Paul A]

Can anyone please suggest where I could start looking in the code for what 
might cause orphaned biblioitems?

Running the following query:

SELECT GROUP_CONCAT('<a target="_blank" href=\"/
cgi-bin/koha/cataloguing/addbiblio.pl?biblionumber=',biblionumber,'\">',biblionumber,'</a>' 
SEPARATOR ', ') AS BibNums,
EXTRACTVALUE(marcxml,'//controlfield[@tag="001"]') AS Id FROM biblioitems
GROUP BY Id HAVING count(Id) > 1;

finds ~0.1% of our total catalogue with orphans -- often, but not quite 
always, they are consecutive biblionumbers leading me to think that this 
happens during cataloguing (but there seems to be no rhyme nor reason as to 
how it happens, we cannot purposefully duplicate the error.)

It's fairly trivial to correct with a " DELETE * FROM biblioitems WHERE 
biblionumber=123456; " but I'd like to stop it from happening in the first 
place.

Thanks for any suggestions,
Paul