[Search] Getting existing Thread suggestions when creating a new topic

Not sure if this is a good place to put this, but I'm on a mission from our vBulletin powered forum, I was telling some of the moderators about another vBulletin powered forum I went too awhile back and explained to them this other forum had a feature that when a person started a new topic it gave a list of similar related topics. we have had a had time recently with lots of people posting the same topics multiple times each day, and its getting out of hand.

is there a name for this module or link I can give them to look into?

thanks,
Nate