Which is better seo wise? Setting URL parameter options in webmasters tools

With respect to all fellow blackhatters..

Can anyone lighten me up with this..
I am using affiliate marketing for a website.
There are users who very often link to the site using their referral links.

For example. If the website url is http://example.com
Users referral link can be http://example.com/?ref=123
All pages with parameter "ref" in url presents same content, same page.

Now, while looking at webmasters tools, I noticed Google found hundreds of backlinks pointing towards urls containing parameter "ref" with different value.

To clarify..
Google found 1000 backlinks pointing to http://example.com
200 backlinks pointing to http://example.com/?ref=123
100 backlinks pointing to http://example.com/?ref=1234
50 backlinks pointing to http://example.com/?ref=12345

Now, inside Google webmasters tools, should I say "this parameter doesnt change content" to let Google know these urls are actually the same page?
Or Does Google attribute total seo value to the basic url (http://example.com)
Or SEO juice is split among those hundreds of urls with different values for the parameter?

Hope i could make myself clear..

Best regards.

Inamon,

Yes you can tell Google which page is the one that should be indexed however you would do that in the source code of the page using rel canonical and not in google webmaster tools.

More on how to use the tag here,

http://support.google.com/webmasters/bin/answer.py?hl=en&answer=139394

Best,

Shawn