HTTP Error 500 - FastCgiModule

In my server I have some classic asp sites, and wordpress sites. I had a problem with my classic asp site, and I manually added "Hendler Mapping" to that site. Unfortunately this Hendler Mapping didn't solve my problem. I solved the problem with a different way. On the other hand, this Hendler Mapping made my wordpress sites stop working. Now classic asp sites are working, but wordpress not. When I enter to my wordpress sites, it gives ", and continues:

HTTP Error 500.0 - Internal Server Error" error
Module FastCgiModule
Notification ExecuteRequestHandler
Handler php-5.5.30
Error Code 0x8007000d
Config Error Cannot add duplicate collection entry of type 'application' with combined key attributes 'fullPath, arguments' respectively set to 'C:\Program Files (x86)\IIS Express\PHP\v5.4\php-cgi.exe, '
Config File \?\C:\inetpub\temp\apppools\alumni.mackosova.com\alumni.mackosova.com.config

Then I deleted the Hendler Mapping that I add, I installed new version of php, and made some other changes but the problem is not fixed yet.

You are experimenting a problem with you configuration files , like the error message says you have a duplicate entry somewhere in your config files ... check this kb article it's for IIS not IIS Express , but maybe this could be useful.

"HTTP Error 500.19" error when you open an IIS 7.0 Webpage - Microsoft Support

extract from the documentation (this is a example not actually the code you must find and replace):

This problem may occur if there is a duplicate entry for the specified configuration section setting at a higher level in the configuration hierarchy (for example, in a parent site/folder’s web.config or applicationHost.config file). The error message itself points out the location of duplicate entry or entries. Examine the specified configuration file and compare it with its parent applicationHost.config and/or web.config files to check for duplicate entries as suggested by the error message. Either remove the duplicate entry, or make the entry unique. For example, this problem may occur because the ApplicationHost.config file has a duplicate entry for the following code.

<add accessType="Allow" users="*" />

To resolve this problem, in the ApplicationHost.config file, delete the duplicate entry for the authorization rule. To do this, follow these steps:

Click Start, type Notepad in the Start Search box, right-click Notepad, and then click Run as administrator. Note If you are prompted for an administrator password or for a confirmation, type the password, or click Continue. On the File menu, click Open, type %windir%\System32\inetsrv\config\applicationHost.config in the File name box, and then click Open. In the ApplicationHost.config file, delete the duplicate entry that resembles the following code:

<add accessType="Allow" users="*" />

if you don't know where to find the config files for IIS Express, you can check Where is the IIS Express configuration / metabase file found?