Why MRP workbench shows additional demand when WIP job order is released from MPS workbench?

Consider following scenarioItem A is FG which requires raw materials B, C & D

After running MRP for Item A system suggests demand for Item B, C & D

If I release requisition for Item B from MRP workbench & then release WIP Job order for item A from MPS workbewnch.

In this case when I am viewing MRP workbench then it shows demand as follows

Item            Qty          Action         Order Number

B                 -1           Demand        WIP Job no.

C                -1            Demand        WIP Job no.

C                -1            Demand       

D               -1             Demand        WIP Job no. 

D                -1            Demand                               ................(Demand should be for 1 Qty only) 

C                2             Release