// filterProperty i.e. 'id' or 'name'
function GetDuplicates(array, filterProperty) {
	//lookup with our intended filter to get the duplicates by a given property
    const lookup = array.reduce((a, e) => {
        a[e.filterProperty] = ++a[e.filterProperty] || 0;
        return a;
    }, {});
    let duplicates = array.filter(e => lookup[e.filterProperty]);
    return duplicates;
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