use strict;

my $regex = qr/(\d\d):(\d\d)(?::(\d\d))?/;

#             01234567890123456
my $string = "11:30 or 11:29:53";

my $res;
while ($string =~ /$regex/g) {
	my $pos = $-[0];
	my ($ind, @match);
	 for $ind (1..$#-) {
	 	push @match, substr ($string, $-[$ind], $+[$ind] - $-[$ind]);
	}
	$res->{$pos} = \@match;
}
use Data::Dumper;
print Data::Dumper::Dumper $res;

##</code><code>##

$VAR1 = {
          '0' => [
                   '11',
                   '30'
                 ],
          '9' => [
                   '11',
                   '29',
                   '53'
                 ]
        };