I was wrong in previous reply. If I put $pua->wait(); there, it is same as LWP::Simple (no paralel). I try to tweak it, but no success (creating another loop, with $pua->agent("$agents[$counter_2]"); $pua->wait();.
You changed my code, so it works now? If not, just try. I have no idea, why it is not working at me, really. Please help.