prevent duplicated owners in metadata amendments

lib/deduplicate.js

@@ -0,0 +1,11 @@
+// remove duplicate elements in an array
+module.exports = function (O) {
+    // make a copy of the original array
+    var A = O.slice();
+    for (var i = 0; i < A.length; i++) {
+        for (var j = i + 1; j < A.length; j++) {
+            if (A[i] === A[j]) { A.splice(j--, 1); }
+        }
+    }
+    return A;
+};