Are there any dual knife styles out there?

Eskrima comes to mind. Normally, we think of it as combat using short sticks, but the original style was designed around using dual blades.

Beyond that, I’m not sure what else to recommend. Neither of us have spent any time studying knife fighting, so we’re not well versed in the formalized knife styles.

Most modern close quarters military training will include some knife forms, but I’m not aware of any that actually employ dual wielding. They may exist, I just don’t know of any.