TLDR: use a password manager to store your secrets. An OTP secret key is just a secret.
Which, to be clear, is perfectly fine. 2fa is completely unnecessary: the increased risk of getting locked out from my accounts and the risk of using services from companies like Twilio and Google is greater than the risk of someone guessing long randomly generated passwords.
That said, the significance of using two separate password stores isn't clear to me. Under what threat model is that supposed to be an improvement over a single password store? Basically, your idea is that passwords are less essential than OTP secrets, so you take less care keeping them safe. However I think it'd make more sense to just apply proper protection for all secrets.