I have not found anything in the specs about the required behaviour when more than one result is found. Any objections to changing to return the first one found?
According to 10.5.6.1 Single-object finder, it should throw FinderException. Doesn't it happen? How can it return null if there are several rows matching the criteria?
I think changing that finder return type to Collection and getting ur required entity from that collection in the code will the alternative for this.
(But it may be like loading unnecessary data :-( )