The short answer to that you probably have to keep both running for a while - if you can afford it.
Most newly purchased medical insurance programs out there will have a 60 to 120-day waiting period for serious diseases like cancer and heart-related illnesses. In other words, your newly purchased policy will not cover you in the event of a claim for heart attacks or anything cancer-related that pops up.
This is a common issue when you first buy into a new medical insurance program. Or in some instances when you upgrade from an older plan.
Your New Medical Insurance Only Covers For Accidents For Now
Your brand new medical insurance plan is as good as a Personal Accident Insurance plan for now. If you're upgrading from an existing plan, this is the risk you'd just have to take. But if you're buying into a new medical insurance program, it is best to keep the existing medical insurance program running for at least the next 120 days. Sure, you'd be paying for both programs (for the time being), but what choice do you have at this juncture?
Assuming you've had your current medical insurance program for more than a year, it provides full coverage for any unforeseen events. And your new medical insurance plan would be good for any accidental injuries at this point.
Worst case scenario. You drop the older medical insurance program and leave yourself exposed for the next 120 days - and it hits the fan. Have I seen it? Yes, once. The client had an infection and was admitted on the 109th day. His claims did not go through.
To simplify it, just calculate what 4 months of premium cost looks like for you and do the Cost vs. Risk analysis from there.