For two different builds to produce identical output, nearly everything about the builds has to be the same. This includes the order in which the linker sees the object files. There is a big difference between presenting the object files directly and presenting those same object files in library. The linker gets an object file from a library only when that file contains the definition of a symbol currently needed. The act of bringing in that object file can cause yet other symbols to become needed. And thus yet more object files are brought in from library. And so it goes. Whatever order of object files this becomes, it is certain to be different than the order used in the non-library link.
Thanks and regards,
-George