Issue with Margin price in POs

In some of the Purchase orders for Raw material (customer provided), we are facing an issue where the rate of the item is fetched from the price list and a margin amount is added to it automatically. This happens in a few cases. Please find the attachment below, the same item is repeated in three lines because of delivery dates. The first line shows the correct price, whereas the 2nd and 3rd lines show a higher rate (where the margin is added).

Please let us know why this is happening. Is there a setting where we can set the default conditions for this or should we only include a pricing rule?

Reference: Discount % or Discount Amt Margin % or Margin Amt - #2 by NCP