Feed.php
public function merge(Feed $feed)
    {
        $this->items = array();

        foreach ($feed as $item) {
            $this->add($item);
        }

        return $this;
    }
public function merge(Feed $feed)
    {
        $this->items = array();

        foreach ($feed as $item) {
            $this->add($item);
        }

        return $this;
    }
Merge 2 feeds

@param Feed $feed
@return Feed