postgres 6.2.1 Group BY BUG

HI

I found some bug:
When I select from table (select A,B,count(*) INTO table tmp1 FROM AAA
group by A,B; ) in
big table some touples are duplicated ;(,

 A,    B,    count(*)
321    1    3    \    ?
321    1    2    /      ?
321    2    5
...........

PS: I use linux 2.0.33 and solaris 2.5.1 and  postgres 6.2.1v7

--
SY, Serj