I think Razer from Young Justice can use both Red and Blue power rings, but I'm not sure how tha tworks.

That means you’re with both Attrocitus and Saint Walker. I’m not sure how that’s possible, because you can’t be both hopeful and angry at the same time.

I don't believe that's possible. Red operates on rage & blue operates on hope. Those 2 essentially oppose each other, in the way yellow (Sinestro Corps) is against green.

It has been established that two rings can be worn at the same time. Hal, John and Guy wore the rings of the other Corps leaders after they were trapped in the book of black, IIRC. I don’t recall the combinations, however there is precedent.

Hope and rage are not opposites. It is clear that the spectrum’s opposites are their opposites. Love and hate (rage), compassion and avarice, hope and fear, with will being a neutral emotion in the centre, which is why it was harnessed by the Guardians. The blue rings, besides empowering the green rings, can assuage the other emotions. Removal if the red rings normally results in the death of the wearer, but with the assistance of the blue rings they can be removed safely.

The blue ring would be the ideal ring to pair with any other due to its ability to not let the unstable emotions consume the bearer.