Sorry Michael, but I don't understand where is the problem

gpsim.i386 and gpsim.x86_64 cannot be installed in parallel, because
these "Makefile"s create file conflicts. That is, their checksums
differ between i386 and x86_64 rpms.

[multi-lib is the concept that makes it possible to install libraries
built for a compatible hardware architecture alongside the libraries
for the native hardware, because both can used by corresponding
executables. For example, on x86_64 the native libs are installed
into /usr/lib64, while the compatible ix86 libs are installed into
/usr/lib. That is the reason why %_libdir expands to different values
on these systems. This also makes it possible to build ix86 binaries
on a x86_64 systems, because you only need to tell the compiler which
architecture to build for and install the needed -devel packages for
that architecture. Due to that, ix86 -devel rpms and their dependencies
are made available in the x86_64 repository.

In the context of this ticket, users of x86_64 hardware, who want to
or need to install gpsim for i386 (as a dependency of some i386 rpms),
could not have gpsim for x86_64 installed already, since both packages
conflict in these files.]

These Makefile are created at rpm build time.
So their checksums differ between i386 and x86_64 rpms.

And I don't know how to fix this problem.
Any idea?

Remove them? They are useless anyway, because they depend on a
various autotools stuff that is only available at build-time.

Btw, some of the examples come with makefiles, which don't work
either.

Humm, I forgot to close it, fixed since 2 weeks.