Feeding Questions

[Abby]

When I picked up my ball python, I was told that he was being fed two small mice on Wednesdays. How exactly should I approach this? Should I place both mice in at the same time? Or should I place one in, let him eat, and then the other right after?

I'm also not sure if I trust the place I bought him from anymore. I don't know his exact hatch date but the worker estimated he was between 3-4 months old. Is feeding him like they have been correct and OK to do?

Any other help regarding feeding would be great. I'm very new to all of this.