Someone just reported a bug to us whereby they were not able to create a list because they were getting a message that they had already registered the list, even though they hadn't. On investigation it turns out that this was when trying to add a life list after already creating a year list, or a self-found list, or another list "type" for the same location. Creating a life list first then adding a variant for the same location was working fine. This must have been happening for a few months without us noticing, so if you have also had this problem before then our apologies. It has now been fixed.