Shipment Confirmation (P4205), Sales Update (R42800) and Item Ledger (P4111)

For a sales order, SO-250099, the standard Shipment Confirmation (P4205, Sts 560-580) with processing option tab “5-Process à 4. Relieve On Hand Inventory Override” equals blank (Relieve Inventory) will create the below entry in the Item Ledger as follows:

UKID = 1234

DOCO = 250099

DCTO = SO

DOC = 250099

DCTO = SO

The Print Invoice (R42565, Sts 580-620), will generate the RI number, RI-250888

While doing the Sales Update (R42800, Sts 620-999), the same item ledger record (UKID =1234 ) will be updated with RI number which generated during the Print Invoice.

So the Item Ledger record will be

UKID = 1234

DOCO = 250099

DCTO = SO

DOC = 250888

DCTO = RI

Now, one of the client is using as customized Shipment Confirmation (P554205) and creating the same line in Item Ledger. But when we run the Sales Update, it creates another record in item ledger. The expected behavior is that it should update the existing line. Where should I check now ?