Possible have 2 php.ini file or 2 extension_dir in php.ini?

Question

i got Fatal error: Class 'mysqli' not found in C:\apache2triad\htdocs\index.php on line 8 error. I checked php.ini file and saw extension=php_mysql.dll is uncommented.Everything is normal. But in php.ini file, it show me extension_dir is

; Directory in which the loadable extensions (modules) reside. extension_dir = "C:\apache2triad\php\extensions"

when i run phpinfo() it show me this:

extension_dir C:\php5 C:\php5