Are you getting duplicate Title warning in Google Webmasters tool? This come when you have same Title meta tag and different URLs. If URL is really different then we need to correct the title tag on Head section. Sometimes we do not have different URLs but the the same URL with different parameters. In this case you do not need multiple title for different parameters. We have canonical link element to use here. It helps us in better SEO.
Use of Canonical link element:
Canonical meta tag is used for telling search engine for semantically getting your pages preferred version among multiple URLs.
Above in image, I do not mean to use different parameters as different pages. So, title is same for all. Google is suggesting to provide different title and suggesting to remove duplicate titles problem.
I have added canonical link element:
<link rel="canonical" href="http://www.satya-weblog.com/tools/php-extensions-list.php" />
It is easy to forget about duplicate title tag in the case above. We see differently than what tool can see.
Suggestion about 'google custom search' pages is correct according to human thinking also. I have different URL (pages) for different purpose. Therefore, I can provide different title (<title>) tag.
(Now, if you are thinking about why these three urls and want to look in details then please blog search in nav bar. )
Just a note that it is not essential that you can use plain url in canonical link element. URL like http://example.com/index.php?cat=php can also be provided. Then all other urls with parameters http://example.com/index.php?cat=php?page=1, http://example.com/index.php?cat=php?page=2 will tell search engine that my preferred URL is http://example.com/index.php?cat=php.