T-SQL Compare two Strings and remove duplicates between them

Some Typos in earlier post

declare @FIRSTNAME nvarchar(100), @LASTNAME nvarchar(100), @NEWFIRSTNAME nvarchar(100), @NEWLASTNAME nvarchar(100)
declare @F1 nvarchar(50),@F2 nvarchar(50),@L1 nvarchar(50),@L2 nvarchar(50)

set @FIRSTNAME= 'Jean ValJean'
SET @LASTNAME= 'Smith Jean'

SET @F1=SUBSTRING(@FIRSTNAME, 1, CHARINDEX(' ', @FIRSTNAME) - 1)
SET @F2=SUBSTRING(@FIRSTNAME, CHARINDEX(' ', @FIRSTNAME) + 1, LEN(@FIRSTNAME))

SET @L1=SUBSTRING(@LASTNAME, 1, CHARINDEX(' ', @LASTNAME) - 1)
SET @L2=SUBSTRING(@LASTNAME, CHARINDEX(' ', @LASTNAME) + 1, LEN(@LASTNAME))

if (@F1=@L2)
BEGIN
SET @NEWLASTNAME=@L1
--@NEWFIRSTNAME=@F2
END
PRINT @NEWLASTNAME

I actually ended up taking care of it by listing both strings into a table variable and then doing a select distinct.  Thank you both - I'm assigning the points half and half.