Why does Create Iteration dialog fail to ensure unique identifier in RTC-3.0.1 ?

Case: Creating a new Iteration in the Timelines section of the Project area configuration. Name the Identifier with a name that is already used.

a) Create iteration by right-clicking an existing Iteration and selecting Duplicate.

Result: Fails - "An iteration with that identifier already exist". OK button not enabled. All good.

b) Create a new iteration by clicking "Create Iteration".

Result: No fail. I am allowed to create another iteration with the same identifier. My Burndown chart gets mixed data.

As I support this product for approx. 800 users, it is problematic that we get error reports from users having strange data in their Burndown chart, spend time trying to figure out whether they did something wrong, only to find out that the problem is non-unique identifiers.

Is there any fix for this in later versions of RTC?