use strict;
use warnings;
use IO::Handle;
use IO::Select;
my $s = IO::Select->new();
...
$s->add(0); # STDIN
$s->add($telnet->fileno());
$s->add($telnet2->fileno());

while(1) {
  my @ready = $s->can_read();
  last unless @ready;
  foreach my $fd (@ready) {
    &handleTelnet1() if $telnet->fileno() == $fd;
    &handleTelnet2() if $telnet2->fileno() == $fd;
    &handleStdin()   if 0 == $fd;
  }
}
...