The original syslinux way seems to also load initrds in a certain order. I suspect the Linux kernel requires the proper order, or the contents of the initrds make differences, I mean, if both initrds contain a file/dir with the same filename/dirname, then last one loaded will take effect.

With



grub4dos will load FILEn first, and FILE1 last(in reverse order), because in this way the coding is simple and easy.