I have a problem with Orchestrator version: 2017.1.6547.
Reference number in the queue is set to unique, and its working fine I cannot add the same number for the second time, to the same queue.
Unfortunately its not working pretty good for postponed items, i am able to add item with same reference number to the same queue 3 or more times. Please take a look on the attached screenshot.
Do you have any ideas why it is happening ?