Topo2: Updated collection to ignore models with the same Id

Change-Id: Ic2faadb76f865921092217bda0aac636349cc1af
diff --git a/web/gui/src/main/webapp/app/view/topo2/topo2Layout.js b/web/gui/src/main/webapp/app/view/topo2/topo2Layout.js
index 97fac88..a64a75b 100644
--- a/web/gui/src/main/webapp/app/view/topo2/topo2Layout.js
+++ b/web/gui/src/main/webapp/app/view/topo2/topo2Layout.js
@@ -230,7 +230,7 @@
                         var regionLinks = t2rs.regionLinks();
 
                         this.link = this.elements.linkG.selectAll('.link')
-                            .data(regionLinks, function (d) { return d.get('key'); });
+                            .data(regionLinks, function (d) { return d.get('id'); });
 
                         // operate on entering links:
                         var entering = this.link.enter()