I test the described scenario with the latest version of the controls and I was not able to reproduce the issue. Entering "Dd" resulted to an empty drop down. I have attached a sample project which demonstrates my tests - could you please check it and let me know if I have missed anything here.
I'm looking forward to hearing from you.
Check out Telerik Analytics, the service which allows developers to discover app usage patterns, analyze user data, log exceptions, solve problems and profile application performance at run time. Watch the videos
and start improving your app based on facts, not hunches.