[Koha] Checkout one item results in multiple items...

[Tim Young]

We have started experiencing a recent issue where attempting to check 
out one item results in multiple of those items (same barcode, checked 
out multiple times) being checked out to the one patron.  This does not 
happen to every item, nor does it happen to every patron.

I am not sure if this error has to do with the problem, but I am seeing 
errors like:

[Tue Oct 10 15:49:58.258993 2017] [cgi:error] [pid 20067] [client 
41.89.41.2:23363] AH01215: [Tue Oct 10 15:49:58 2017] additem.pl: 
DBIx::Class::Storage::DBI::select_single(): Query returned more than one 
row.  SQL that returns multiple rows is DEPRECATED for ->find and 
->single at /usr/share/koha/lib/Koha/Objects.pm line 92, referer: 
http://opac.scott.ac.ke:8080/cgi-bin/koha/cataloguing/additem.pl?op=edititem&biblionumber=15157&itemnumber=25724

showing up in the internet-error.log

Any clue how I should begin tracking this down?

     - Tim