I've been trying to edit my legend on a line chart to use different symbols for each field in the series. My output on the actual chart is showing correctly, where each series had a different symbol, but my legend duplicates the series, one showing the original shapes with the correct colors, the other showing the correct shapes with the wrong color (just black). Am I missing something about how these properties need to be combined so it's not duplicated? Thanks in advance for the help.

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {"url": "data/barley.json"},
  "layer": [
    {
      "mark": {"type": "line", "tooltip": true, "interpolate": "linear"},
      "encoding": {
        "stroke": {"field": "site", "type": "nominal", "legend": null},
        "opacity": {
          "condition": {
            "test": {"field": "__selected__", "equal": "false"},
            "value": 0.3
          },
          "value": 1
        }
      }
    },
    {
      "mark": {"type": "point"},
      "encoding": {
        "shape": {"field": "site", "type": "nominal"},
        "color": {"field": "site", "type": "nominal"},
        "opacity": {
          "condition": {
            "test": {"field": "__selected__", "equal": "false"},
            "value": 0.3
          },
          "value": 1
        }
      }
    }
  ],
  "encoding": {
    "y": {
      "field": "variety",
      "type": "nominal",
      "axis": {"grid": true},
      "sort": {
        "op": "average",
        "field": "All Except Difference",
        "order": "descending"
      }
    },
    "x": {
      "field": "yield",
      "type": "quantitative",
      "sort": {
        "op": "average",
        "field": "All Except Difference",
        "order": "descending"
      },
      "scale": {"zero": false}
    }
  }
}