group by bug in 6.2.1 & 6.3 -snapshot

Hi

I find next bug:
in query "select a,b,count(*) from q group by a,b;" postgres do:
a    ,b    ,count(*)
5    2    3    ???
5    2    2    ???
6    3    6
.................

table - about 10000-30000 tuples.

PS: i use linux 2.0.33 & solaris 2.5.1

--
SY, Serj