Kyle,
I am using cb antispam. And I am using Captcha v2. I did check the keys and the antispam_captcga field is visible and published. I did also disable the cache and purged it. Nothing seems to help.
The only difference that I can see is that both sites run on a different hosting provider, use a slightly different template and have a different module layout. Also one of the sites uses one language. The other uses 2 languages.
But both sites use the cblogin module for login and the settings for these modules are identical.
Robert