Hey...I love Chick tracts!Nero's cross, you mean the thing made up in the 50s and 60s to try to attack the counter-culture movement that wanted British nuclear disarmament? "Nero's cross" is allegorical at best and has no known extant examples.
The closest thing in reality is St Peter's Cross which is just an upside down cross, that is not the same symbol.
I'm starting to think people here use Chick tracts as sources of their knowledge of the world.
But I tend to agree with you that similarities in design don’t necessarily lend credence to similarity in purpose or origin.