Duplication of demands in Multifacility MRP


The MRP program R3483 has generated duplicate demands for few items and as a result it has generated wrong MRP messages and displays duplicate demands (multiple lines) in Supply/Demand screen.
For example, the item # ABC(Purchased raw material) & # XYZ (semi finished item) has demand from 2 work orders in next 7 days (say 28th & 29th July) of 1000 & 2000 units each. The total demand is 3000 units. The supply /demand screen should display demand as 1000 units as on 28th July and 2000 units as on 29th July in the normal scenario. However in this case after R3483 run, supply/demand screen displays several lines of same demand (1000 & 2000 units) with corresponding work order details. Here it displays/repeats the demand 20 times with same datas. This duplication is as result of wrong calculation of MRP program and population of F3412 table with duplicate demands.
The brief background of about setup:
All the items (including purchased raw materials, semi finished & finished manufactured items) have Planning fence rule of “F” (use Forecast qty within rule and use Forecast + Customer Demand qty outside rule) and Planning code of 2 (planned by MRP) for both supply & demand branch plants.

The typical process involves work orders have been created to produce semi finished goods in Demand B/P A (Make to Stock). Then semi finished goods are sent to Supply B/P B for conversion process. The converted product sent back to Demand B/P A again to produce finished goods (Make to Order).

As part of multi facility setup, the B/P relationship has been setup using Branch plants without specifying the item or planning family group. No sales forecast is being used and only open work orders are considered as demand and planned orders generated by MRP are considered as Supply along with PO.

Can you tell me what could be the reason for duplication of these demands after every run of R3483.



Here is some idea.
Is there the same result if you try to run R3482?
Have you had forecast quantities for them besides they were already on sales orders?