As per Marina's suggestions:

1. Add a 3rd parameter to the function get_all_user_name_fields() which specifies a prefix for the retrieved sql fields.
2. adding a new function that does a reverse mapping, i.e. to substitute repeating pieces of code like

   $allnames = get_all_user_name_fields();

   foreach ($allnames as $allname) {

   $tempname = 'creator' . $allname;

   if (isset($question->$tempname)) {

   $u->$allname = $question->$tempname;

   }

   }

   or the same without prefix

   $allnames = get_all_user_name_fields();

   foreach ($allnames as $addname) {

   $userinfo[$reviewer->reviewerid]->$addname = $reviewer->$addname;

   }