Planned order created for delivered Qty during MRP Run

Dear Experts

                     We are using PS+PP+SD Scenario .

Issue

            1.  Reservation created against project activity with Mov 281 .

             2.MRP RUN MD51, Pld>Prd>Stock Genration.

            3 Then MRP Run and found results are Ok

            Issue starts when I PGI This quantity and then again Run MRP,system again genrated pld for PGI Qty.

Where PGI qty affecting Cust Ord in MD4C and displaying requirement after PGI (OK)

Example :

                 Reservation = 100MT

                 PLD >PRD>STOCK =100MT

                 MRP run and found  stock=100 MTOK

                 PGI through VL01N = 50 MT

                MRP run and found following result

                pld =50 MT & Stock -50MT.

         Plz suggect