Here's a Schwartzian Transform solution (assuming your numbers don't exceed 12 digits):

print join "\n",
  map  { join ',', @{$_->[0]} }
  sort { $a->[1] cmp $b->[1] }
  map  { my $x; for(@$_){$x.=sprintf("%012d",$_)}; [$_,$x] }
  @un_sorted;
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