Can someone explain price and discounts?

[Gajillion]

I've written a script to parse my Digikey invoices and populate Part-DB with all the relevant information via the API, but I'm really struggling with calls to /api/parsedetails. What exactly do "Minimum discount quantity", "price", and "for amount" map to? When I receive price breakdowns, I get

  {
      "BreakQuantity": 10,
      "UnitPrice": 0.754,
      "TotalPrice": 7.54
  },

I also get

        "Quantity": "2",
        "PricePaid": "$0.76 "

What corresponds to what and how do you input it via the API? Adding the first price breakdown always works:

{
        "orderdetail": "/api/orderdetails/410",
        "price": "0.93",
        "minimum_discount_quantity": 1,
        "price_related_quantity": 1
  }

But any subsequent attempts to input anything else always fail with

  "detail": "min_discount_quantity: This value is already used.",
  "description": "min_discount_quantity: This value is already used.",

even if I don't use min_discount_quantity:

{
        "orderdetail": "/api/orderdetails/410",
        "price": "0.732",
        "price_related_quantity": 10
}

Any ideas? It appears "Minimum discount quantity" gets auto-populated with quantities of 10, so I tried manually changing all of my discount and related quantities to odd numbers and it fails the same way.