problem with unicode search, return invalid results

i have following text coming in data

Unicode Text Unicode Entities
三田屋はむ %u4E09 %u7530 %20 %u5C4B %20 %u306F %u3080
三田屋ハム %u4E09 %u7530 %20 %u5C4B %20 %u30CF %u30E0

both strings are clearly different however when i execute following queries than both return same result (i.e. 三田屋ハム)

select   * 
from   (
       select N'三田 屋 ハム' as a union
       select N'三田 屋 はむ' 
     ) a 
where   a = N'三田 屋 ハム'

select   * 
from   (
       select N'三田 屋 ハム' as a union
       select N'三田 屋 はむ' 
     ) a 
where   a = N'三田 屋 はむ'

i get valid result for following query

select    * 
from    (
            --select N'三田 屋 ハム' as a union
            select N'三田 屋 はむ' a
        ) a 
where    a = N'三田 屋 はむ'

i have checked the Unicode value and both are differnt

select UNICODE(N'三'), UNICODE(N'田'), UNICODE(N'屋'), UNICODE(N'ハ'), UNICODE(N'ム') union 
select UNICODE(N'三'), UNICODE(N'田'), UNICODE(N'屋'), UNICODE(N'は'), UNICODE(N'む')

can someone please let me know if i am missing something here. thanks.