$ ./two_digit_combo.pl | perl -ne 'print join " ", sort unpack("A2" x (length()/2), $_)'
00 01 02 03 04 05 06 07 08 09 11 12 13 14 15 16 17 18 19 22 23 24 25 26 27 28 29 33 34 35 36 37 38 39 44 45 46 47 48 49 55 56 57 58 59 66 67 68 69 77 78 79 88 89 99

$ cat two_digit_combo.pl                        
#!/usr/local/bin/perl

for('00'..'99'){$h{$_}++if(!($h{$_}||$h{reverse$_}))}print keys%h

$