General Question-Advice On Same Website 2 Countries

Ill try to keep it short.

One of my main keyword competitors in the UK that tend to jockey with position for me has appeared while I was searching google when on holiday in the US but with a diiferent url extension.

Their usual url in the Uk ends .com but the one I picked up on while holidaying in the US is .US.

Site is identical except showing $ and shipping changes etc.

IP address is the same and I am wondering is this a whole new site or would it have a geotargeted type of trigger that alters just the needed information.

But then comes the question of duplicate content in the eyes of Google, would it not attract huge penalties. We already ship quite a lot to the USA and am wondering should I try and follow a similar path if is possible with CS.