URLEncode returns a different value in ASP classic and PHP

I am developing an application that should integrate with PayPal. To do this, it calls some call through the API, and in these calls I have to pass some parameters that are URLEncoded. My problem is that I did not work, because Server.URLEncode of the classic asp returns something strange to me.

See below:

@CODEPAGE="65001"    
Response.Charset = "UTF-8"
response.write(server.URLEncode("xxxx_1344559025_biz_api1.yy.com"))

This string returns me: xxxx% 5F1344559025% 5Fbiz% 5Fapi1% 2Eyy% 2Ecom

Same thing in php

echo(urlencode('xxxx_1344559025_biz_api1.yy.com'));

It returns me this line: xxxx_1344559025_biz_api1.yy.com

Both files are encoded in UTF-8, I do it on DreamWeaver with CTRL + J> title / encoding

Does anyone know why I get such an answer in ASP classic and PHP?

Thanks in advance for your help.