Just tried to PM all duplicate memebr accounts using the option in the acp for this
Got this error
INSERT INTO `core_message_topic_user_map` ( `map_user_id`, `map_topic_id`, `map_folder_id`, `map_read_time`, `map_user_active`, `map_user_banned`, `map_has_unread`, `map_is_system`, `map_is_starter`, `map_left_time`, `map_ignore_notification`, `map_last_topic_reply` ) VALUES ( NULL, 879, 'myconvo', 0, true, false, true, false, false, 0, false, 1512406019 )
IPS\Db\Exception: Column 'map_user_id' cannot be null (1048)
#0 /public_html/system/Db/Db.php(807): IPS\_Db->preparedQuery('/*IPS\\core\\Mess...', Array)
#1 /public_html/applications/core/sources/Messenger/Conversation.php(616): IPS\_Db->insert('core_message_to...', Array)
#2 /public_html/applications/cjdml/sources/Actions/Actions.php(204): IPS\core\Messenger\_Conversation->authorize(Array)
#3 /public_html/system/Dispatcher/Controller.php(85): IPS\cjdml\modules\admin\acp\_duplicates->pm()
#4 [internal function]: IPS\Dispatcher\_Controller->execute()
#5/public_html/init.php(448) : eval()'d code(29): call_user_func_array('parent::execute', Array)
#6 /public_html/applications/cjdml/modules/admin/acp/duplicates.php(48): IPS\Dispatcher\hook26->execute()
#7 /public_html/system/Dispatcher/Dispatcher.php(146): IPS\cjdml\modules\admin\acp\_duplicates->execute()
#8 5/public_html/admin/index.php(13): IPS\_Dispatcher->run()
#9 {main}