How do I handle 2 employees who are demanding immediate pay for their final pay. I believe that I have to pay final pay next pay period. In nj.

I have 2 employees one quit one was let go. They are demanding immediate pay because they think I owe them back pay. I am up to date on their pay it's just they don't understand biweekly payroll and think I'm behind. I've tried being reasonable and explain to them and even trying to pay them early but now they are becoming threatening and unreasonable and have family members harassing us as well. How do I handle this situation without it becoming a legal problem? I never denied them pay and will pay final check on next pay date as per my labor laws in nj. I don't know how else to explain when they get final pay since they are demanding it immediately or they are threatening legal action.