1. you can provide the Completion Requirement Check in Maint. Plan i.e. further call/orders will not be generated without completing existing released call/orders.
or can change the sch. period of 4 years to 6m, 12 years etc.
2. handling of duplicate orders- change the basic start/finish date as next call date (as per freq. 3m, 6m) & use these duplicate orders during next scheduled time but in maint. plan do skip next call to auto-generate.