Think is really a bug
Took a look at source of groupnewedit.php file and looks like
function checkForDuplicate($data)
is using a variable not defined (or more precisely not correctly spelt)
I have amended to use groupid and it looks like that has fixed my issue
$groiupid -> $groupid
Can you include in next release
I have paid for this module so I would have expected better support on this issue
I indicated that the error message was wrong and related to group saving, not member saving
It was easy to duplicate - in fact saving any existing group would probably have given the error
Daniel