Being male and female or not doesn't make a difference for snakes. They need to be separated. It's "quite hard breeding them" because they are both stressed and shouldn't be housed together. Stress in a ball python is not necessarily visible.
It may look "fine" to inexperienced owners, just because nobody is getting hurt, but they need to compete for the warmest spot, the most ideal hide, and the risk of cannibalism is something that happens within a few minutes, and it kills them both. The one who eats the other doesn't live either. Just because nothing "happened" visibly to you yet isn't a reason.
You'll also need a thermostat for your heat pad, or you risk burns too:
https://www.amazon.com/MTPRTC-ETL-Ce...stat+hydrofarm