This SQL had the desired effect. Join wasn't even needed.
$result3 = mysql_query( "SELECT login.firstname, login.lastname, test.questionone, test.questiontwo, test.questionthree, test.questionfour, test.questionfive, test.questionsix, test.questionseven, test.questioneight, test.questionnine, test.questionten, test.questioneleven, test.questiontwelve, test.totalscore FROM login ,test WHERE login.registration = '45rt6n2' AND test.id = login.id GROUP BY login.lastname" );