Here's a simple way to do it with POE. Keep in mind that there will be at minimum a one second delay before each check for a new event. More importantly, if the NextEvent() calls block (which I'm guessing they do from your code), you could wait longer than one second on a given check, meanwhile events from the other generator could be happening. That's the trouble with blocking calls. I didn't feel like copying 90% of your code, so you'll need to replace the ...'s with the relevant portions.

#!/usr/bin/perl

use strict;
use warnings;

use POE;

POE::Session->create(
    inline_states => {
        _start => \&init,
        check_creation => \&check_creation,
        check_deletion => \&check_deletion,
    },
);

$poe_kernel->run();
exit 0;

sub init {
    my ( $kernel, $heap ) = @_[ KERNEL, HEAP ];

    # make creation event logger thingie
    $query = ...; # the creation one
    ...
    $heap->{ creator } = $wbemsvc->ExecNotificationQuery( $query );

    # make deletion event logger thingie
    $query = ...; # the deletion one
    ...
    $heap->{ deletor } = $wbemsvc->ExecNotificationQuery( $query );

    $kernel->delay_set( check_creation => 1 );
    $kernel->delay_set( check_deletion => 1 );
}

sub check_creation {
    my ( $kernel, $heap );

    my $wbeobj = $heap->{ creator }->NextEvent();
    my $msg = $wbeobj->{ TargetInstance }->{ Message };
    # ... do the message stuff here

    $kernel->delay_set( check_creation => 1 );
}

sub check_deletion {
    my ( $kernel, $heap );

    my $wbeobj = $heap->{ deletor }->NextEvent();
    my $msg = $wbeobj->{ TargetInstance }->{ Message };
    # ... do the message stuff here

    $kernel->delay_set( check_deletion => 1 );
}
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