while (<IN>) {
    our(@F) = split(/\s+/, $_, 0);
    push @{$r{join ' ' x 8, @F[0..3]};}, [@F[4, 6]];
    sub END {
        foreach $k (keys %r) {
            my($x, $y);
            map {$x += $$_[0]; $y += $$_[1];} @{$r{$k};};
            my @g = split(/\s+/,$k);
            print OUT "$g[0]\t@g[1]\t@g[2]\t@g[3]\t", $x / scalar(@{$r{$k};}), "\t$y\n";
        }
    }
}

##</code><code>##

while (<IN>) {
    our(@F) = split(/\s+/, $_, 0);
    push @{$r{join ' ' x 8, @F[0..3]};}, [@F[4, 6]];
}

... all other code ...

END {
    foreach $k (keys %r) {
        my($x, $y);
        map {$x += $$_[0]; $y += $$_[1];} @{$r{$k};};
        my @g = split(/\s+/,$k);
        print OUT "$g[0]\t@g[1]\t@g[2]\t@g[3]\t", $x / scalar(@{$r{$k};}), "\t$y\n";
    }
}