This will come close to what you want:

declare @two table (id int, value int)

insert into @one select 1, 11 union all select 2, 12 union all select 3, 13 union all select 4, 14

insert into @two select 1, 21 union all select 2, 21 union all select 1, 31 union all select 2, 32

select *

from @one one

full outer join @two two

on one.id = two.id

Only the duplicates of the non-matching rows won't be produced by the above query.

Edit: I see Chriss provided a sample including the duplicates...