my @col1;
my @col2;

my $t = 0;

foreach (sort {$hash{$b} <=> $hash{$a} || $b cmp $a} keys %hash) {
   if ($t ^= 1) {
      push(@col1, $_);
   } else {
      push(@col2, $_);
   }
}

printf "%s\t%s\n", pop(@col1), pop(@col2)
   while @col2;

printf "%s\n", pop(@col1)
   while @col1;