;with SampleDataR as
(
select *, ROW_NUMBER() over (partition by title, subtitle order by value) rownum
from test12
)
select distinct title, subtitle,(
select value
+ case when s1.rownum = (select MAX(rownum) from SampleDataR where title = s1.title and subtitle = s1.subtitle)
then '' else ',' end from SampleDataR s1
where s1.title = s2.title and s1.subtitle = s2.subtitle
for xml path(''),type).value('(.)[1]','varchar(max)') csvList
from SampleDataR s2