set nocount on
create table prep
(tkey int, param float)
insert into prep values ( 1 ,rand())
insert into prep values ( 1 ,rand())
insert into prep values ( 2 ,rand())
insert into prep values ( 2 ,rand())
insert into prep values ( 2 ,rand())
insert into prep values ( 3 ,rand())
insert into prep values ( 4 ,rand())
go
select max(tkey) tkey, max(param) param  into #temp from prep pp
group by tkey 
having count(tkey)> 1 

delete prep from #temp where prep.tkey=#temp.tkey

insert into prep select * from #temp

select * from prep

go
drop table #temp
drop table prep