Request that uses both calculated and ordered dosage

{
  "resourceType" : "MedicationRequest",
  "id" : "medrx003",
  "identifier" : [{
    "use" : "official",
    "system" : "http://www.bmc.nl/portal/prescriptions",
    "value" : "12345689"
  }],
  "status" : "completed",
  "intent" : "order",
  "medication" : {
    "concept" : {
      "coding" : [{
        "system" : "http://snomed.info/sct",
        "code" : "80582002",
        "display" : "Glycerol (substance)"
      }]
    }
  },
  "subject" : {
    "reference" : "Patient/pat1",
    "display" : "Donald Duck"
  },
  "authoredOn" : "2015-01-15",
  "requester" : {
    "reference" : "Practitioner/f007",
    "display" : "Patrick Pump"
  },
  "dosageInstruction" : [{
    "sequence" : 1,
    "text" : "1800 mg (1000 mg/m2) orally twice daily from days 1-14 of cycle",
    "doseAndRate" : [{
      "type" : {
        "coding" : [{
          "system" : "http://terminology.hl7.org/CodeSystem/dose-rate-type",
          "code" : "calculated",
          "display" : "Calculated"
        }]
      },
      "doseQuantity" : {
        "value" : 1800,
        "unit" : "mg/m2",
        "system" : "http://unitsofmeasure.org",
        "code" : "mg/m2"
      }
    },
    {
      "type" : {
        "coding" : [{
          "system" : "http://terminology.hl7.org/CodeSystem/dose-rate-type",
          "code" : "ordered",
          "display" : "ordered"
        }]
      },
      "doseQuantity" : {
        "value" : 1000,
        "unit" : "mg",
        "system" : "http://unitsofmeasure.org",
        "code" : "mg"
      }
    }]
  }]
}