Save session: deduplicate nub dependencies messages

src/app/app.component.ts

@@ -551,13 +551,17 @@ export class AppComponent implements OnInit, OnDestroy, Observer {
     for (const c of this._calculators) {
       const uid = c["uid"];
       const nub = Session.getInstance().findNubByUid(uid);
+      let required = nub.getTargettedNubs().map((req) => {
+        return req.uid;
+      });
+      required = required.filter(
+        (item, index) => required.indexOf(item) === index // deduplicate
+      );
       list.push({
         "children": nub.getChildren().map((child) => {
           return child.uid;
         }),
-        "requires": nub.getTargettedNubs().map((req) => {
-          return req.uid;
-        }),
+        "requires": required,
         "selected": form ? (uid === form.uid) : true,
         "title": c["title"],
         "uid": uid