HI Sandeep,
Notificaiotn N1 creating order Z1 in background by user Exit.
But order Z1 is also creating N1 in background.
two possible options
1) As suggested by sir Jogeswara, remove configuration setting. Because you are starting your process form Notification only. i.e. breakdown maintenance .
Generally we create notification in background when corrective maintenance order is created.
2) implement an implicit enhancement for IW31 program, which will check whether a notification is already assigned to an order or not. If notification exist, order wont create one more notification.
Regards,
Amol