declare @pivottest table (strUserId nvarchar(20), strProductId nvarchar(20) )

insert into @pivottest values ( 'A12345', 'product1' )
insert into @pivottest values ( '12345', 'product1' )
insert into @pivottest values ( 'A5678', 'product2' )
insert into @pivottest values ( '5678', 'product2' )

strUserId            strProductId
-------------------- --------------------
A12345               product1
12345                product1
A5678                product2
5678                 product2

product1             product2
-------------------- --------------------
A12345               A5678
12345                5678

select * from
( select strUserId, strProductId from @pivottest ) sq
pivot
(
max(strUserId)
	for strProductId in ([product1],[product2])	
) piv

select product1, product2 from
( select strUserId
       , strProductId
       , rn = row_number() over (partition by strProductID order by strUserId) from @pivottest 
       ) sq
pivot
(
max(strUserId)
	for strProductId in ([product1],[product2])	
) piv