How to add blank rows between groups of duplicate rows?

Question

here is my setup
create table #tmpA(rowID int identity(1,1), fName varchar(10), lName varchar(10))
insert into #tmpA
select 'a', 'b' union all
select 'a', 'b' union all
select 'c', 'd' union all
select 'c', 'd' union all
select 'e', 'f' union all
select 'e', 'f' union all
select 'g', 'h' union all
select 'g', 'h'
select distinct fName, lName
into #tmpB
From #tmpA
select t1.* from #tmpA t1 Join #tmpB t2 on t1.fName = t2.fName and t1.lName = t2.lName
--output
rowID  fName  lName
1             a         b
2             a         b
3             c         d
4             c         d
5             e         f
6             e         f
7             g         h
8             g         h
I want to add blank rows between rows 2 & 3 and between rows 4 & 5 and between rows 6 & 7 in the join query above.  Is there Tsql that can accomplish something like this to make the join query result look like the following output?
rowID  fName  lName
1            a          b
2            a          b
3            c          d
4            c          d
5            e          f
6            e          f
7            g          h
8            g          h
or if this is not possible I could go with an output like this:
rowID  fName  lName
1             a         b
2             a         b
3
4             c         d
5             c         d
6
7             e         f
8             e         f
9
10           g         h
11           g         h
Rich P

Answer 1

I came up with the following on my own.  I was just hoping there might be a fancier way to do this - like without looping -- and yes, I could/should do this in a presentation layer, but I just wanted to do this in Query Analyzer (or whatever they call
it now -- SSMS ...) -- BTW, thanks CELKO for the suggestion about how to insert multiple rows using Values -- works great.
If (object_id('tempdb..#tmpA') is not null) drop table #tmpA
If (object_id('tempdb..#tmpC') is not null) drop table #tmpC
create table #tmpA(rowID int identity(1,1), fName varchar(10), lName varchar(10))
insert into #tmpA
values
('a','b'),
('a','b'),
('c','d'),
('c','d'),
('e','f'),
('e','f'),
('g','h'),
('g','h')
create table #tmpC(rrowID int Identity(1,1), rowID int, fName varchar(10), lName varchar(10))
declare @i int, @s varchar(10), @t varchar(10), @u varchar(10), @v varchar(10)
select @i = min(rowID) from #tmpA
set @u = 'xx'
While (@u != 'yy')
Begin
   select @s = fName, @t = lName from #tmpA Where rowID = @i
   if exists(select 1 from #tmpA Where rowID = @i + 1)
      select @u = fname, @v = lName From #tmpA Where rowID = @i + 1
   else
      set @u = 'yy'
    if @s = @u And @t = @v
       begin  
         Insert Into #tmpC(rowID, fName, lName) Select * from #tmpA Where rowID = @i
         Insert Into #tmpC(rowID, fName, lName) Select * from #tmpA Where rowID = @i + 1
       end      
    else
       begin
          Insert Into #tmpC(rowID, fName, lName) Select null, '', ''  
       end
    set @i = @i + 1
End
select * from #tmpC
--output from #tmpC
rrowID  rowID  fName  lName
  1            1         a        b
  2            2         a        b
  3          NULL 
  4            3         c        d
  5            4         c        d
  6          NULL  
  7             5         e        f
  8             6         e        f
  9           NULL  
  10           7          g        h
  11           8          g        h
  12         NULL  
Rich P