For a while I've been seeing a bug in Activiti Explorer's User Cache that seemed to be caused by having several users with the same name. I finally found the time to write some failing tests, and it seems to be an issue with the RadixTreeImpl directly. I don't have time to dig into it, nor do I have a jira account, but the 5 source files are attached below. Let me know if you need it in another format. I tried to attach a patch file but the form wouldn't let me.