DECLARE  @table TABLE 
(  
   [Name] varchar(15),
   [Order] varchar(15), 
   [Month] varchar(15),
   [Detail] varchar(15),
   [Value] numeric(10,2),
   [Margin]  numeric(10,2)
)
insert into @table([Name], [Order] ,[Month] ,[Detail] ,[Value] ,[Margin])
          select 'Fred' ,'Ord1', 'Month2', 'Ace', 1300, 400
union all select 'Fred' ,'Ord2', 'Month2' ,'Long', 0 ,-15010
union all select 'Fred' ,'Ord3', 'Month2' ,'Bing', 2270 ,309.09
union all select 'Fred' ,'Ord4', 'Month1' ,'Stuff', 6471.6, 5383.81
union all select 'Fred' ,'Ord4', 'Month2' ,'Stuff', 3275, -462.79
union all select 'Fred' ,'Ord5', 'Month2' ,'Roof' ,4940 ,1140.72
union all select 'Fred' ,'Ord6', 'Month2' ,'Wall' ,12545, 2110.37

;with cte as
(
  select [Name], [Order] ,[Month] ,[Detail] ,[Value] ,[Margin] , 
  row_number() over(partition by [Order] order by [Order]) rn from @table 
),
only_one as
(
  select [order] from cte group by [order] having count(*) = 1
),
multiple as
(
  select * from cte where [order] in (select distinct [Order] from cte where rn > 1)
)
select [Name], [Order] ,[Month] ,[Detail] ,[Value] ,[Margin] from cte
where [order] in (select [order] from  only_one)
union all 
select t1.[Name], t1.[Order] ,t1.[Month] ,t1.[Detail] ,t1.[Value]-t2.[Value] [Value]
       , t1.[Margin] -t2.[Margin]  [Margin] 
from multiple t1 
cross join 
    multiple t2
where t1.rn = 2 and t2.rn = 1 

DECLARE @temp AS TABLE

(v1 INT, v2 INT, v3 INT)

INSERT INTO @temp

SELECT 1,3, NULL UNION ALL
SELECT 3,4,5 UNION ALL
SELECT 4,2, NULL UNION ALL
SELECT 3,4, NULL UNION ALL
SELECT 2, NULL, NULL

SELECT DISTINCT
cp.*

FROM
@temp
CROSS APPLY (
	SELECT Newcol
	FROM (VALUES (v1), (v2), (v3)) X (Newcol) 
) cp