The main issue is it can be hard for both snakes to get what they need if the other one is already in the spot they need. As in if they both want the warm hide. They may not fit so they can both get the heat they desire leaving one stuck out.
If the cage was big enough to offer more than one heat spot and cool spot you would be much better off. I don't believe the tank they are in is really large enough for the two.
Personally Id get them two nice pvc cages and get them set up each with their own space.
As for the reptile carpet Ive never used it and from what I have seen it is not that great of an option. I use a mixture of cypress, Eco, and Repti Bark.
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A red bulb is fine.