Duplicate duplicate identifier errors

[mjbvz]

From microsoft/vscode#43554

TypeScript Version: 2.8.0-dev-0211

Search Terms:

• Duplicate identifier

Code

class Point {

    constructor(private x?: number, private y?: number) {

    }

    get x() {
        return this.x;
    }

}

Bug
Two duplicate errors for line 7 are returned:

[Trace  - 14:56:00] Event received: semanticDiag (0).
Data: {
    "file": "/Users/matb/projects/san/src/Button.ts",
    "diagnostics": [
        {
            "start": {
                "line": 3,
                "offset": 25
            },
            "end": {
                "line": 3,
                "offset": 26
            },
            "text": "Duplicate identifier 'x'.",
            "code": 2300,
            "category": "error"
        },
        {
            "start": {
                "line": 7,
                "offset": 9
            },
            "end": {
                "line": 7,
                "offset": 10
            },
            "text": "Duplicate identifier 'x'.",
            "code": 2300,
            "category": "error"
        },
        {
            "start": {
                "line": 7,
                "offset": 9
            },
            "end": {
                "line": 7,
                "offset": 10
            },
            "text": "Duplicate identifier 'x'.",
            "code": 2300,
            "category": "error"
        }
    ]
}

[mhegazy]

PRs welcomed. At this point it is not clear why we have the extra error message, so that is where i would look first.