curl --request POST \
  --url https://{deployment}/api/v1/notion/bulk-duplicate-check \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <api-key>' \
  --header 'X-Notion-Token: <api-key>' \
  --data '
{
  "notion_id": "26f...",
  "lookup_properties": [
    "Email"
  ],
  "records": [
    {
      "Email": "a@b.com"
    }
  ]
}
'

{
  "success": true,
  "total": 123,
  "existing_count": 123,
  "unique_count": 123,
  "results": [
    {
      "index": 123,
      "lookup_key": "<string>",
      "exists": true,
      "match_count": 123,
      "matched_page_ids": [
        "<string>"
      ],
      "record": {}
    }
  ],
  "unique_records": [
    {}
  ],
  "duplicate_records": [
    {}
  ]
}