Allow different CAPTCHA for different registrations

Problem/Motivation

I would like to have a CAPTCHA for the main registration form but not for a special simplified registration form that I use to register many people in a row at events. They both have the same ID so I can't figure out how to only show the captcha on the original.

Proposed resolution

Add a unique ID that can be targeted by CAPTCHA but not break functionality? I don't know enough about how things work if the ID affects other things.