Why not see what it does and work it out... 
perl -MData::Dumper -e '
my @AoA=(
["one", "two", "three"],
["four", "five", "six"],
["four","five","six"], 
["seven", "eight", "nine"],
["eight", "seven", "nine"]);
my @r = grep{++$uniq{ join $; , sort @$_ } == 1 } @AoA; 
print "\@r is now:\n", Dumper(\@r), "\%uniq is now:\n",Dumper(\%uniq)'

[download]
Then check out $; in perlvar.

print "Good ",qw(night morning afternoon evening)[(localtime)[2]/6]," fellow monks."

In reply to Re: code explanation by Utilitarian
in thread code explanation by ramdat

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