If all you need to do is limit the number of simultaneous but otherwise identical connections, Parallel::ForkManager should do the trick. You might have to add a little more logic if you need to use a different target port for each connection, but that's just a pop/push stack.

my @portlist = qw/10001 10002 10003 10004/;

use Parallel::ForkManager;
$pm = Parallel::ForkManager->new(scalar @portlist);

foreach my $target (@targets) {
    my $pid = $pm->start and next; 

    my $port = pop @portlist;
    system("telnet $target $port");
    push @portlist, $port;

    $pm->finish; # Terminates the child process
}
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