use feature qw(say);
use strict;
use warnings;

use Getopt::Long;

my( @opt_a, @opt_b );

GetOptions(
           'a=s{2}' => \@opt_a,
           'b=s{2}' => \@opt_b,
          );

say "@opt_a";
say "@opt_b";


##</code><code>##

./pm-886569 -a a1 a2 -b b1 b2
a1 a2
b1 b2