Image tool creates duplicate object with 0x0 dimensions

[simoneduca]

See zooniverse/shakespeares_world#164 for replicating

Json blob from Local Storage

[
    {
        "type": "image",
        "x": "320.75",
        "y": "413",
        "width": "23.19999999999999",
        "height": "32.49000000000001"
    },
    {
        "type": "image",
        "x": "408.92",
        "y": "491.89",
        "width": "46.39999999999998",
        "height": "51.05000000000007"
    },
    {
        "type": "image",
        "x": "408.92",
        "y": "491.89",
        "width": "0",
        "height": "0"
    }
]