P:\test>perl -e"print sort { $b <=> $a || $b cmp $a } qw/0a 0b 1a 1b/"
1b1a0b0a

P:\test>perl -e"print reverse sort { $a <=> $b || $a cmp $b } qw/0a 0b 1a 1b/"
1b1a0b0a