SharePoint Online Remote Event Receiver - ItemUpdated Event Triggers multiple times

I'm trying to update the list item using RER (Provider Hosted App + SharePoint Online) and the problem is that the ItemUpdated event is is triggered multiple times. 

Any suggestions? 

AppEventReceiver.cs

public SPRemoteEventResult ProcessEvent(SPRemoteEventProperties properties)
        {

            SPRemoteEventResult result = new SPRemoteEventResult();

            switch (properties.EventType)
            {
                case SPRemoteEventType.AppInstalled:
                    HandleAppInstalled(properties);
                    break;
                case SPRemoteEventType.AppUninstalling:
                    HandleAppUninstalling(properties);
                    break;
                case SPRemoteEventType.ItemAdded:
                    HandleItemAdded(properties);
                    break;
                case SPRemoteEventType.ItemUpdated:
                    HandleItemUpdated(properties);
                    break;
            }

            return result;
        }

private void HandleItemUpdated(SPRemoteEventProperties properties)
        {
            using (ClientContext clientContext =
                TokenHelper.CreateRemoteEventReceiverClientContext(properties))
            {
                if (clientContext != null)
                {
                    new RemoteEventReceiverManager().ItemUpdatedToListEventHandler(clientContext, properties.ItemEventProperties.ListId, properties.ItemEventProperties.ListItemId); 
                }
            }

        }

RemoteEventReceiverManager.cs

public void ItemUpdatedToListEventHandler(ClientContext clientContext, Guid listId, int listItemId)
        {
            try
            {
                List photos = clientContext.Web.Lists.GetById(listId);
                ListItem item = photos.GetItemById(listItemId);
                clientContext.Load(item);
                clientContext.ExecuteQuery();

                DateTime lastModifiedTime = Convert.ToDateTime(item["Modified"].ToString());

                if (lastModifiedTime < DateTime.Now.AddMilliseconds(-2))
                {
                    item["Description"] += "\nUpdated by RER " +
                    System.DateTime.Now.ToLongTimeString();
                    item.Update();
                    clientContext.ExecuteQuery();
                }                
            }
            catch (Exception oops)
            {
                System.Diagnostics.Trace.WriteLine(oops.Message);
            }
        }