The usage of the Track Changes feature is quite relevant information when it comes to RadEditor. With the used version, there might be issues. Recently, improving the Track Changes functionality was an ongoing task and many improvements has been done.
Due to that, I suggest considering to upgrade the used version to a more recent one (best-case scenario - using the latest one - 2014 Q3). You can test the same feature in a real-live example in this online demo
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.