I agree with Kevin. You should have separate setups just in case.

BUT at 3:19 in the video, the camera person has to drop the camera to separate two frogs. I think that says a lot! And the general way they look at each other, just ready to strike at the slightest movement.

I personally, would never put them together. Maybe, try the same size females, like John.

BUT all other times I would separate them. My pixies are to valuable to me to have one eat another.

jmo