Yes, you can charge customers at the same time by logging into a single HitPay account on multiple devices (Desktop and Mobile).
However, we recommend creating individual user access for your staff to prevent password sharing. This way, each staff will have their own login access to the HitPay account. This is especially useful when you have company staff distributed across multiple locations and collecting payments on behalf of your company or business.
You can refer to the user management guide for further information.