Does it hurt you in any way? If not - I would just leave it alone. Google can tell a copy from original. I tried to search some arbitrary text from your website - there is no trace of copycat in Google SERP.
What striked me, though, is that a copycat website is waaaay faster than your original. If I were in your shoes, I would invest my time and effort into speeding up the site. Unlike hunting some script kiddies, that will bring palpable benefits.
Bing is directing searches for their service to the fake web site, which is then serving up porn after a few seconds delay. I'd say it is hurting them.
What striked me, though, is that a copycat website is waaaay faster than your original. If I were in your shoes, I would invest my time and effort into speeding up the site. Unlike hunting some script kiddies, that will bring palpable benefits.