We are using OKTA now for SSO, but we will slowly moving to Rippling. • Is it possible to have two SSO tools active in Netsuite at the same time during the transition?

as far as I can tell, there is only one identity provider's meta data can be added to the system. Don't see any option to add multiple providers in SSO setup screen. I might be wrong.

I think you are right. I didn't see any option to add more than one. I was hopping to slowly move people instead of having to do this all at once.