Disallowing *.php

I created custom php pages in my root folder
www.mywebsite.com/page.php

Now I've got Google Webmaster Tools telling me of a duplicate content
which is
www.mywebsite.com/page.php
and
rewritten URL
www.mywebsite.com/page/

So what to do

Is it safe to include (Disallow: *.php) in robots.txt

Am afraid the other pages won't be crawled and so missing organic traffic

Please advise

Do you have any other pages with the .php extension that you want indexed? If so, just disallow: page.php

Originally Posted by Michael Biddle

Do you have any other pages with the .php extension that you want indexed? If so, just disallow: page.php

Yes I have many of them (12 pages)
Should disallow all of them
I've got problem with only one of them so far

Why do you want me to avoid (Disallow: *.php)

Well if you want to index the .php files then obiously you would want to stay away from *.php. However, if you have rewritten all of the links to be something like page/ and want to remove duplicates with the .php and the other, than yes, you should use the *.php.

why not seo them pages and disallow php all together..

How do I make sure that all my php pages are redirected by vbSEO?
So if this is a basic question but am new to this

I do not know how to know which links show in php automatically. Only way I know is scroll over all links and check the extension.