My site allows more than one user to use the same email address. So Tom, Jane and Mary can all be registered using the same address. I have selected Group commentors based on user names but it appears that if Tom has 3 comments, Jane has 1 and Mary has 1 then only Tom appears listed on the widget with 5 comments beside his name.
The site is used by children so Tom is happy but Jane and Mary feel cheated! :)
Any help appreciated.