use warnings;
use strict;
use Getopt::Long;

my @actions;
GetOptions(
  first  => sub { push @actions, \&first },
  second => sub { push @actions, \&second },
) or die "Invalid options passed to $0\n";

sub first {
  print "Processing sub first\n";
}

sub second {
  print "Processing sub second\n";
}

$_->() for @actions;

__END__

$ perl 11140961c.pl --first --second --first --second --second --first
Processing sub first
Processing sub second
Processing sub first
Processing sub second
Processing sub second
Processing sub first
$ perl 11140961c.pl --first --second --year --first --second --second --first
Unknown option: year
Invalid options passed to 11140961c.pl