Does CST_INV_LAYERS create a Unique Layer ID, Inv_Layer_id for every Inventory Receipt?

Hello All,

We got a requirement to match the Sales order issues to the Respective Material Inbound Transaction (May be PO Receipt or RMA or Miscellaneous receipt). Since we are using FIFO costing, I thought that the easiest way is to use CST_INV_LAYERS, MTL_CST_ACTUAL_COST_DETAILS to map the Outbound (SO) to Inbound...

But to my surprise, I saw two Miscellaneous receipts with the same Layer and Inv Layer ID in MTL_CST_ACTUAL_COST_DETAILS. This is happening if the cost of both the receiving transaction are same.

When I cross checked CST_INV_LAYERS, I saw that there's only one row with the sum of Receipt Quantity there. The Create Transaction ID was pointing to the Last Miscellaneous Receipt Transaction.