Supplemental Index Woes

I have very large vBulletin forums and have noticed that all the search engines are indexing many of the same page with various urls, even though I bock all pages except for showthread.php in robots.txt.

For instance... google has indexed the following versions of the same showthread.php thread:

/showthread.php?p=48043&mode=linear
/showthread.php?mode=hybrid&t=2491
/showthread.php?t=2490&goto=nextoldest
/showthread.php?p=48043&page=2&pp=25
/showthread.php?t=2491&page=1&pp=25
/showthread.php?goto=lastpost&t=2491
/showthread.php?p=50108&mode=linear
/showthread.php?p=48043&mode=threaded
/showthread.php?p=50108&mode=threaded

NOTE: All these links point to the EXACT same thread!!!

I have looked around at other vB forums on the net and no one else has
this problem. Is there anyway to stop this? Thanks for your help!

Actually - all vBulletin powered forums that are NOT yet running vBSEO, HAVE this problem.

vBSEO will enable your forum to be 1-URL-Per-Resource, eliminating both duplicate content and duplicate paths to the same content (if you prefer to think of it that way).

The only way to stop this behaviour is to vBSEO-enable your forum.