I often see people write, that you can not have 2 visas at the same time. I have an O-A visa. I just applied and got an METV also. The O-A expires later this month. I am coming for 6 months, and would prefer to use the O-A as I would not have to leave the country and/or extend. I bought a travel insurance as it has much better coverage than a health insurance. It is also much cheaper.
I would prefer to use the O-A, but I doubt it will be accepted without a normal health insurance.
Will it be a problem to come with 2 visas and ask if I can use the O-A. If I can not, I will use the METV.
If I am not allowed to have 2 visas, maybe I should not try to ask.