How to duplicate a page

I’m using the Highend theme, and instead of just editing one of the pages from the demo site (Default page – left sidebar), I want to duplicate it. I want to keep the demo page as-is for reference.

I have found a plug-in that will copy or duplicate a page or post (Duplicate Post), but it is untested with my version of WordPress (4.0).

Is there any way I can copy/duplicate a page or post? Or is it safe to install and use this plug-in?

Thanks for your help,
Patty