If it is true that someone sent in two blank swabs and it came back positive then the test is totally worthless and should not be relied upon whatsoever.
I had covid in March. If I tested positive now, I would absolutely not self quarantine, as I don’t believe it’s possible to get it again.
I actually know of people who tested positive even though that they were for sure over covid. That being the case, I don’t trust the results at all, and I see no reason for anyone to self quarantine as a result of positive test.
If you live in areas where the virus is raging, then everyone who did not already have the virus should be careful. But if you live in a place like New York, then just go about your business, unless you have symptoms that indicate that you have the virus, or you are high risk.