It should work, but it doesn't. Back in the dark ages when I did the code, I foolishly chose to use a comma to separate the various recipient options. I should have user ||. Then this would probably work:
If you feel like living dangerously, try changing line 158 of the spformproc.class.php file from this:
$recipientArray = explode(',',$recipientArray);
to this:
$recipientArray = explode('||',$recipientArray);
Then change line 312 of the nearby spform.class.php file from this:
$this->spfconfig['recipientArray'] = explode(',',$ra);
to this:
$this->spfconfig['recipientArray'] = explode('||',$ra);
Then change the format of the recipientArray property as described at the beginning of this post.
Be prepared to revert all the changes if it doesn't work.