I tried to reproduce the issue you are describing with the latest assemblies - I am deleting one appointment and then creating a new one, but the UniqueIDs look different. Attached I am sending you a short video for reference.
Could you please share more details how to reproduce the problem - ultimately, if you could send us a sample where this issue can be observed, it will be very helpful for tracking down the source of the problem in a timely manner.
Looking forward to your reply.
the Telerik team