Watch only tracks last file if given array of files

[Rarst]

This is my watch task:

/**
 * Watches for changes.
 */
public function watch() {

    $this->taskWatch()->monitor( array( 'css/variables.less', 'css/laps.less' ), function () {
        $this->less();
    } )->run();
}

It names both files correctly when started:

c:\server\www\dev\wp-content\plugins\laps>robo watch
 [Robo\Task\WatchTask] watching css/variables.less for changes...
 [Robo\Task\WatchTask] watching css/laps.less for changes...

But only last file is tracked, changes to first file do not trigger task. If I reverse order of files in array it flips and again — only last file in array is tracked, other one is ignored.

Win7x64, PHP 5.5

PS ok, now I am not sure if this is even supposed to work?.. :) For some reason I was under impression it is.

[DavertMik]

sorry, probably I didn't check this case as I was completely relying on lurker library. Looks like i need to fix this