Checks whether we need to modify document, before change - on display name change.

modules/UI/side_pannels/contactlist/ContactList.js

     },
 
     onDisplayNameChange (id, displayName) {
+        if(!displayName)
+            return;
         if (id === 'localVideoContainer') {
             id = APP.conference.localId;
         }
         let contactName = $(`#contacts #${id}>p`);
 
-        if (displayName) {
+        if (contactName.text() !== displayName) {
             contactName.text(displayName);
         }
     },

modules/UI/videolayout/RemoteVideo.js

     // If we already have a display name for this video.
     if (nameSpan.length > 0) {
         if (displayName && displayName.length > 0) {
-            $('#' + this.videoSpanId + '_name').text(displayName);
+            var displaynameSpan = $('#' + this.videoSpanId + '_name');
+            if (displaynameSpan.text() !== displayName)
+                displaynameSpan.text(displayName);
         }
         else if (key && key.length > 0) {
             var nameHtml = APP.translation.generateTranslationHTML(key);