How to create two security verifications for registration?
 

I tried the search, so please forgive me if this has been discussed previously.

I've been getting a TON of spam registrations. I've done all the security changes as suggested here. However, it still seems they keep coming. I'd like instead to add in an additional security question other than the single one I have now. A site that comes to mind that does this is LS1GTO.com. See here:

http://www.ls1gto.com/forums/register.php?

They use both an Image Verification and a NoSpam! question. How do I do this, or does it require a hack (and if so, can you point me in the right direction?)?

Thanks in advance!