Hi @wjhtomwjh,
You have definitely come across one of the DB-relates issues with the experimental 1.11.8a4 version. To avoid the problem you've experienced, I'd like to recommend upgrading to the latest 1.11.9 release that alleviates the problem of duplicates that 1.11.8a4 was meant to solve. One thing to note, though, is that 1.11.9is a patch on 1.11.8 so it uses the same DB setup. Please, check 1.11.9 release post for more details.