By Kai Germaschewski:

 "Well, I have another solution, which doesn't need additional Makefile
  magic or anything.

  I just put the module name into each .o file where <linux/module.h> is
  included. Putting it into the section .gnu.linkonce.modname has the effect
  that even for multi-part modules, we only end up with one copy of the
  name.

  Caveat: I'm using the preprocessor macro KBUILD_MODNAME to know what to
  put into .gnu.linkonce.modname. The following used to happen:

  (drivers/isdn/eicon/Makefile)

  divas-objs := common.o Divas_mod.o ...
  eicon-objs := common.o eicon_mod.o ...

  Divas_mod.o is compiled with -DKBUILD_MODNAME=divas
  eicon_mod.o is compiled with -DKBUILD_MODNAME=eicon
  common.o is compiled with -DKBUILD_MODNAME=divas_eicon

  So in the case above, both divas.o and eicon.o would end up with
  a .gnu.linkonce.modname section containing "divas_eicon"

  My fix to this is to not define KBUILD_MODNAME when compiling an object
  whilch will be linked into more than one module - so common.o gets no
  .gnu.linkonce.modname section at all. Works fine here.

  Now, doing this I remove one of the reasons why we would need modules
  linked as '.ko' ;), but it seems much cleaner than generating a temporary
  file, using objcopy etc."