Strange HTTP headers show the same URL twice

[joeliu]

This is so strange that the http header show the same url twice:

http://example.com/home.html

GET /home.html HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-TW; rv:1.9.0.10) Gecko/2009042316 Firefox/3.0.10
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-tw,en-us;q=0.7,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: Big5,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://example.com/home.html
Cookie: __unam=ff611ea-121c61ef92e-7d0ca25d-4; PHPSESSID=g4cu6pdclgqverrf2a522uofl1

HTTP/1.x 200 OK
Date: Thu, 11 Jun 2009 13:15:13 GMT
Server: Apache/2.2.8 (Fedora)
X-Powered-By: PHP/5.2.6
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 2979
Connection: close
Content-Type: text/html; charset=UTF-8
----------------------------------------------------------
http://example.com/home.html

GET /home.html HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-TW; rv:1.9.0.10) Gecko/2009042316 Firefox/3.0.10
Accept: image/png,image/*;q=0.8,*/*;q=0.5
Accept-Language: zh-tw,en-us;q=0.7,en;q=0.3
Accept-Encoding: gzip,deflate
Accept-Charset: Big5,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://example.com/home.html
Cookie: __unam=ff611ea-121c61ef92e-7d0ca25d-4; PHPSESSID=g4cu6pdclgqverrf2a522uofl1

HTTP/1.x 200 OK
Date: Thu, 11 Jun 2009 13:15:14 GMT
Server: Apache/2.2.8 (Fedora)
X-Powered-By: PHP/5.2.6
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Vary: Accept-Encoding
Content-Encoding: gzip
Content-Length: 2979
Connection: close
Content-Type: text/html; charset=UTF-8

----------------------------------------------------------

what i know is the only difference is the "Accept". My question is how to reduce request to one time. And "Expires: Thu, 19 Nov 1981 08:52:00 GMT" affect SEO? Thank in advance :)

Server:
fedora 7, apache 2, php 5 and mysql 5

[edited by: encyclo at 11:06 pm (utc) on June 11, 2009]
[edit reason] switched to example.com [/edit]

[coopster]

Welcome to WebmasterWorld, joeliu.

Check your source code for home.html and see if you have an additional href or src attribute looking for that very same resource. Looks like it may be an image element, or at first glance that seems suspect anyway.

[encyclo]

Welcome to the forums joeliu. :) I agree that this is appears to be the server responding to two separate requests by the browser, so either you are actually requesting the resource twice or you have a link to the same resource in your HTML as coopster above mentions.

And "Expires: Thu, 19 Nov 1981 08:52:00 GMT" affect SEO?

A date in the past simply tells the user agent not to cache the resource, it is normal for dynamic sites and will not be detrimental for SEO.

[joeliu]

Thank you coopster :)
Thank you encyclo :)

The problem is solved. The problem is from hacking lightbox 2 of prototype and Script.aculo.us. When i try to remove the loading.gif in /img and its related code in lightbox.js, there is extra request shown in http header.