Hi,
Comments 4.2 (I don't know if this applies also to new version).
Because of some spam we had to enable recaptcha for public.
In configuration recaptcha is enabled and enabled ONLY for Public usergroup.
Problem is recaptcha is in forms for everyone - for registered and even for super users, of course, when they are logged in.

This is how it should work? Maybe my files are not up to date.
I checked component code and joomla classes, problem is here:
$userGroups = $user->getAuthorisedGroups();
and for Super Users it contains IDs of all usergroups.
Agter changing this line into
$userGroups = JAccess::getGroupsByUser($user->id, false); ( function getGroupsByUser($userId, $recursive = true) )
I see only selected usergropus for logged in user and now recaptcha works only for public.