I've not been able to confidently follow what the parent wrote, but if they're discussing diverse double compiling, the way it works is that you compile the sam

I've not been able to confidently follow what the parent wrote, but if they're discussing diverse double compiling, the way it works is that you compile the same source code (S) with a bunch of different compilers (C0...CN). This gives you a bunch of executables (E0...EN) which are the compilation of S. Because C0...CN are different compilers, E0...EN will probably differ, bitwise. But because behavior should depend only on the source code, if those compilers are sufficiently correct E0...EN should behave the same. So if you compile S with E0...EN to get (say) E0'...EN', those should all be bitwise identical.