Overdue letters are sent twice because of wrong default values usage in overduerules tables. This patch modifies default values in database and looks for default rules to apply. To reproduce the bug, define different overdue rules for branches and default site. Set different email address for KohaAdminEmail and branch email. Run overdue_notices.pl -n and look at messages generated in message_queue table
Created attachment 3695 [details] [review] Change default value in overduerules table for delayn (NULL instead of 0) and fix GetBranchcodesWithOverdueRules function
Not an enhancement, changing it to a bug, so it is still eligible for 3.4
Pushed, please test
There have been no further reports of problems so I am marking this bug resolved.