Neo4j Spatial Index Cross Linked.... How did it happen, and how do I fix it?

Question

I've got a large Neo4J spatial database with around 1.5 million nodes in it.

It's come to my attention that the spatial index is corrupted - some nodes are cross linked:

match (n)<-[:RTREE_REFERENCE]-(a)<--(c),(n)<-[:RTREE_REFERENCE]-(b)<--(c) where id(a) <> id(b) return n,a,b,c limit 1;

returns:

{"table": {
    "_response": {
        "columns": ["n", "a", "b", "c"],
        "data": [
            {
                "row": [
                    {
                        "wkt": "POINT (374075.17 164903.59)",
                        "id": 525155,
                        "gtype": 1,
                        "bbox_abc": [374075.17, 164903.59, 374075.17, 164903.59]
                    },
                    {
                        "bbox_xx": [374075.17, 164903.59, 374075.17, 164903.59]
                    },
                    {
                        "bbox_xx": [374075.17, 164903.59, 374075.17, 164903.59]
                    },
                    {
                        "bbox_xx": [373539, 164601, 376045, 165462]
                    }
                ],

     ======= CUT ======
    "nodeMap": {
        "118052": {
            "bbox_xx": [374075.17, 164903.59, 374075.17, 164903.59]
        },
        "525156": {
            "wkt": "POINT (374075.17 164903.59)",
            "id": 525155,
            "gtype": 1,
            "bbox_abc": [374075.17, 164903.59, 374075.17, 164903.59]
        },
        "845986": {
            "bbox_xx": [373539, 164601, 376045, 165462]
        },
        "846042": {
            "bbox_xx": [374075.17, 164903.59, 374075.17, 164903.59]
        }
    },
}}

I thought that spatial index nodes ought to have a single RTREE_REFERENCE. How is it possible that mine has two. There are about 115 such nodes in the database with this issue.