Why are there two different OpenSSL.exe ?

[lhannegu]

Hello
I have integrated SimpleSAMLphp with my application in XAMPP in the root directory "htdocs".
Everything works fine, up to a point where openssl_verify() fails, and the support team is wondering whether something is wrong with the OpenSSL library configuration on my machine.
It took me a while to discover that I had to create an OPENSSL_CONF environment variable.
I made the environment variable point to D:\xampp\php\extras\openssl\openssl.conf, without any modification in the config file.
Is this correct ?
But then I saw that there are two different versions of openssl.exe in XAMPP alone.
There is one in Xampp/Apache/bin
And another in Xampp/hp/extras/openssl/
Why ?
Where can I find a document that explains their use, and the recommended configuration in Windows XP (environment variables, which DLLs to copy to windows system directory, how to check which is put into play, etc.) ?

Thank you
Best regards
Laurence