I have a site with URL formats...

mysite.com/link.html

They all have a .html extension.

Problem: Concrete5 pages have .php extension. How do I work around it?

I plan to migrate one by one the pages in Concrete 5 using the same name as the current page link. I've changed the code so that Concrete 5 automatically uses "-" instead of "_".

I'm using pretty URLs.

Everything is working. Except it appears the Concrete 5 page extension are .php.

What is the best way to make the transition without bad SEO ramifications?

I'm aware that the mode rewrite will make any .html links track back to the .php Concrete 5 page. My fear is that this might be considered duplicate content.

I've hacked the site code so that .html pages run like .php. Is there a simple way to get Concrete 5 to use .html rather then .php?

Or is doing that asking for trouble?

If I can't get native .html extensions from Concrete 5 do I need to do a 301 re-direct from every .html extension to the .php extension?

OR...

Does doing that cause looping problems between the re-direct and the mod rewrite?

Is there a simpler solutions?

Thanks for your help... this community (and CMS) has been remarkable so far.