The only nut round here is you.

Jack, the fly in the ointment is always the fallibility of testing. Someone who has "had the virus twice" would (a) have been tested twice, at the right time, months apart, (b) been tested twice via an ultra-reliable test. (a) would be very unusual. (b) is currently nowhere near achievable. Not saying for one second that you can't catch it twice. But this type of virus does generally confer some immunity, if only for a short time, and, let's face it, the disease has only been in the domain of the known for not much more than half a year. "Catching it twice" is, as far as I can see, still in the realm of rumour.