Andrew, there are a couple of puzzling pieces of information in your posting

1. The as-shipped /admin/orders.php for zc157c does, in fact, provide the NOTIFY_ADMIN_ORDERS_SHOW_ORDER_DIFFERENCE notification.

2. The SQL statement in EO's init_eo_config.php that's inserting that statement is, in the as-distributed v4.6.2 file, uses INSERT IGNOREas opposed to just plain old INSERT.