Post Getting different/wrong data in temporary table

Hi

when I am executing this statement I am getting 18 rows(which is correct).
select * from Table1 t1,Table2 t2 where t1.ID=t2.ID;


but when I am storing result in to temp table #temp I am getting 2942928 rows in temp table(which is replication of above 18 rows)
select * into #temp from Table1 t1,Table2 t2 where t1.ID=t2.ID;


Anybody knows what may be the issue?