Do you want them to hatch chicks or not? What do you want to happen, maybe we can help you get there. I'll do some "if's".
If that is the only egg you want to try to hatch (no guarantee it will actually hatch) break that other broody now. I've had broody hens fight over eggs when they start to pip, they destroyed half the eggs. Don't take that chance, break one from being broody now.
If you want them both to hatch eggs, get some fertile eggs for the second broody. Do not split those eggs between the two hens. That way you would have a staggered hatch with that one egg. You do not want a staggered hatch, those are stressful to you and often unsuccessful.. If I did that I would isolate one of those hens so they could not both get to the eggs.
If you can find day-old chicks you can give them to that second broody. If you want to go that route we can talk techniques. Again I'd isolate one of the hens.
If you want a different outcome tell us what it is.