Each duplicate question has up to three other questions as the non-duplicate posts. This query finds the posts that duplicate questions point to. It mostly works, but no guarantees.
Q&A for community managers, administrators, and moderators
select top 200 PostId as [Post Link], Text,
charindex(']', Text) - charindex('[', Text) - 1) as [Post Link]
from PostHistory h
where PostHistoryTypeId = 10
and Comment in (1, 101)
order by CreationDate desc