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Had some problems with these a while back. Are you using a 301/302 redirect? Are they appearing as url only or are they appearing fully indexed? If they are fully indexed then what are they indexed with? A year ago I seen 301 tracking redirect urls indexed with content of the page the redirect was on. Just a funny thing I seen happened. If they are URL only then more than likely it shows that google knows about the url since it is placed on a public page and they simply do nothing with them.
There are some form pages that I use for discussion posts that use the same script and url except for the query strings. I just put the forms in a seperate directory and disallow the whole directory plus disallow on page to be safe. Works real well. There are many variations due to query strings and google knows about those urls since they are on public pages (they show in site-maps and one version in the site: command) but does not index any contents of those pages.
You could also be safe and put a rel="nofollow" in the href tags containing the links. Keep in mind that google will still know of the url but again should do nothing with it and if any were displayed they should be url only.
using the line "disallow: /*.php$" in my robots.txt file would prevent them from indexing php files.