How to stop KDE Connect SMS treating direct chat as group chat?

I have a strange problem with KDE Connect SMS. I am in a direct SMS chat with one person. It isn’t a group chat. However KDE Connect SMS treats it as a group chat and includes my number as an additional member of the group. What this means is that I get sent a copy of messages direct to my phone number as well as having 2 copies of messages in the “group”. How can I fix this?