Create Table #A (Ln NVarchar( 20 ),FN NVarchar ( 20 ),TheDate DateTime)
Create Table #B (Ln NVarchar( 20 ),FN NVarchar ( 20 ),TheDate DateTime)

Insert Into #A Values ('Иванов','Вася','20010101')
Insert Into #A Values ('Козлов','Петя','20010101')
Insert Into #A Values ('Крылов','Саша','20010101')

Insert Into #B Values ('Иванов','Вася','20010101')
Insert Into #B Values ('Козлов','Петя','20010101')
Insert Into #B Values ('Вагина','Лена','20020101')

Select #A.*
From #A INNER JOIN #B On #A.Ln = #B.Ln And #A.FN = #B.Fn
UNION 
Select #B.*
From #B LEFT JOIN #A On #A.Ln = #B.Ln And #A.FN = #B.Fn
Where #A.Fn Is Null