You can legally own a Medical Aid and a Health Insurance policy at the same time. However, it is important to remember that you cannot claim from both of them for the same event. This is a general rule of insurance.
When do they not work together?
Short answer is when they cover the same things. You cannot claim for medical events from more than one insurance policy, wether that is a Medical Aid or a Health Insurance (with a Long or Short Term Insurance license).
So taking out a Medical Aid with a health insurance hospital plan is not advised as you would only be able to claim from the Medical Aid for hospital related events.
This is a general rule of course. If your health insurance policy covers something that your medical aid does not and you really need that cover, then you might consider taking out both but we would strongly suggest seeking advice from a consultant first to make sure you don't run into problems down the line.
What about Gap Cover?
Gap cover is a special exception to this general rule as Gap cover is designed to insure you against a shortfall in your Medical Aid cover. It covers the "gap" between what the Medical Aid covers and what your final bill was.
Why would you want a Medical Aid and a Health Insurance plan?
The short answer is that they can complement each other quite well if you choose them correctly.
Medical Aids are designed to cover hospital events really well. Sure, they have higher premiums but they are fantastic products when you need to be admitted to hospital.
However, they are not designed to cover out-of-hospital expenses like health insurance does. They tend to rely on the limited Medical Savings Account (MSA) for this purpose. So if you take out a Day-to-Day plan with your Medical Aid then you can get the best of both worlds, if it suits your needs.
With Episodic, you can get to choose whether you want a Day-to-Day plan, a Hospital Plan or both so it is really easy to create a policy that can work with a Medical Aid by choosing just the Day-to-Day plan.