Scrape links via PHP SDK vs Explorer

Question

I'd like to know the difference between using scrape via PHP sdk and Explorer, in my particular case using SDK PHP I have a function in a class basically with this little snippet of code

 try{
        $scrape = $this->getFacebook()->post('/',array (
            'scrape' => 'true',
            'id' => $link
        ),
            $accessToken
        );
       $data['link'] = $link;
       $post = $this->getFacebook()->post('/',$data, $accessToken);
       return $post;

    }
    catch(FacebookResponseException $e) {
        return $this->validateToken($e);
    } catch(FacebookSDKException $e) {
        return sprintf('Facebook SDK returned an error: ' . $e->getMessage());
    }

My question is, if I make some changes in my page($link) metas such as og:image, I have to run this code 2-4 times to see changes in the facebook post related to this link however I use Facebook Explorer Tool directly, then I post and changes are corrected to the first attempt.. Any Ideas>?? Thanks in advance!!!!!!