Several of the flaws and virtues have an asterisk next to them, but I can't find a single mention of what information that's supposed to impart.
I believe that they denote virtues or flaws which might be taken multiple times. Serf's Parma.
Indeed, it is to indicate that theses lab virtues and flaws can be taken more than once.
(Covenants p.113, second paragraph of the section "Laboratory Virtues and Flaws".)