Can we have two urls with two extension in same site?

[saraem]

Hi all,

Can we have two types of extensions in same site.
For eg :
Case : 1
domainname.com/property-one.htm

Case : 2
domainname.com/property-two.php

So, the url points different pages, but in my site some pages are in htm extensions and some pages are in php extensions.

Will it affect SEO.. ??
Thanks for your suggestions in advance.