Duplication of enumerated specs

[yhoonkim]

When I ran this query with the transformed dataset below, it made 24 specQueryModel but 12 of them are duplicated.

Data

// data is loaded from '../datasets/cars.json'
data = data.map(d => {return {"Origin": d.Origin};});

Query

{
  "spec": {
    "mark": "point",
    "encodings": [
      {
        "channel": "?",
        "field": "Origin",
        "type": "nominal",
        "sort": { "field":"?", "op":"mean", "order":"?"}
      },{
        "channel": "?",
        "field": "Origin",
        "type": "nominal",
        "sort": { "field":"?", "op":"mean", "order":"?"}
      },{
        "channel": "y",
        "field": "*",
        "type": "quantitative",
        "aggregate": "count"
      }
    ]
  },
  "config": {
    "autoAddCount": true,
    "overlay": {
      "line": false
    }
  }
}