Redmine

via right click, duplicate a ticket
change some fields (subject, status, assignee, target and a couple of others )
I did not change the project or tracker
specifically for the assignee I emptied the setting so that it was not assigned to anyone.
click create

The new issue has all the settings correct expect the assignee. It was not empty it was the second last person in the list. That person was never assigned to the original issue.