Fix T71199: Child-parent relationships arent kept after you make instances real.

Comparison function of the of the parent ghash was not fully correct,
could lead to some false positives in some cases...

source/blender/editors/object/object_add.c

@@ -1714,7 +1714,11 @@ static bool dupliobject_cmp(const void *a_, const void *b_)
     return true;
   }
 
-  if (ELEM(a->type, b->type, OB_DUPLICOLLECTION)) {
+  if (a->type != b->type) {
+    return true;
+  }
+
+  if (a->type == OB_DUPLICOLLECTION) {
     for (int i = 1; (i < MAX_DUPLI_RECUR); i++) {
       if (a->persistent_id[i] != b->persistent_id[i]) {
         return true;