The quickest and easiest answer to most questions in husbandry is what would happen in the wild. In the wild, Ball Pythons are not communal and do not engage in herd behavior. They get together for copulation and that's about it. They are solitary animals and don't appreciate the company. Other problems can also occur.
1. One snake dominates the other for heat / food / water and can be aggressive.
2. Stress can lead to increased risks for anorexia, infections and bad temperment.
3. Infections can be spread.

It's just a bad idea. Not good for the animal at all.