This is one current limitation with No Page Comment.
The plugin does a check to see if it is a new post, avoiding any possible way to reset settings on pages you are editing.
Unfortunately, with plugins that create the page first and then bring you right to the Edit Page screen, I have no way to tell if it's a "new" page or not. I've most often noticed this with duplicating posts or pages.
It's in my todo list to see if there's a solution, but I currently don't have the time, and also believe that as each of the duplication/insert new plugins have their own functions, I probably can't create a "one size fits all" solution.
My only option may be to create a hook in my plugin, so other plugin or theme authors can use that with their own function if needed. But, I'm limited on time right now, so that probably won't be set up or looked at for a while.
Sorry for the inconvenience.