Getting penalized for identical pages

[bcc1234]

Hi, is it possible to get penalized for having identical pages on the site ?

On one of my sites - the following URLs produce identical output:

mysite.com/
mysite.com/home.jsp
mysyte.com/DisplayPage?site.refnum=1&page.refnum=1
mysyte.com/DisplayPage?page.refnum=1&site.refnum=1

It's all the same page.

Also, pages like:
/DisplayPage?site.refnum=15&page.refnum=7&cat.refnum=34
and
/DisplayPage?site.refnum=15&cat.refnum=34&page.refnum=7

I have different links throughout the site, can that hurt my listing ?

Thanks.

[ciml]

Google deals quite well with duplicates, often merging their listings and sometimes crediting the remaining listing with links to both URLs.

Sometimes, though, duplicates cause confusion. If each of the /DisplayPage?whatever addresses are duplicates of some other address then I'd ban spidering via robots.txt (which is often how shopping cart sites are approached).

[bcc1234]

Sometimes, though, duplicates cause confusion. If each of the /DisplayPage?whatever addresses are duplicates of some other address then I'd ban spidering via robots.txt (which is often how shopping cart sites are approached).

What I mean is:
some page on the site has links to it as
/page.jsp?par1=val2&par2=val2
and the same page has other links
/page.jsp?par2=val2&par1=val2

Which is the same for application but makes a different URL.

Can I get penalized for that ?

[jesserud]

Fix your links to use a canonical form. It's ok if two URLs produce the same page, but only one of those URLs should be linked to. It may or may not help Google, but it will help your visitors, who like visited links to appear differently from unvisited links. Cooperating with the browser's visited-links feature prevents the visitor from feeling like he's going in circles. (Other techniques for not driving the user in circles: don't change the colors for visited and unvisited links, try to use the same text whenever you link to a given page, and don't re-use text or an image to link to two different pages.)

For your home page, I recommend that you use the URL /. / looks better as a search result and is easy to recognize in the status bar. It might also save you a few bytes of bandwidth :P