Is that Googlebot or some other robot? They don’t always play by the rules, but you can advise robots which pages should not be crawled by adding the robots.txt file to your site root (see
Google Webmaster Guidelines).
By default it should look something like this for modx:
# Default modx exclusions
User-agent: *
Disallow: /assets/cache/
Disallow: /assets/docs/
Disallow: /assets/export/
Disallow: /assets/import/
Disallow: /assets/modules/
Disallow: /assets/plugins/
Disallow: /assets/snippets/
Disallow: /install/
Disallow: /manager/
Also, check to see that
<meta name="robots" content="noindex, nofollow" />
appears in your page header...
