Hi Jay,
Did you ever get a resolution to your ticket?
I am seeing a very similar issue to your first problem when trying to run mlnx_add_kernel_support.sh against a kernel derived from 3.12.44 in sles12. Like you there were no problems building the modules against sles11sp3.
The error message I am seeing is in the "else" part of the error handling of function make_id_link() in find-debuginfo.sh which is used in RPM packaging (the message you quote is in the "if" part of the error handling):
objcopy: '/tmp/mlnx_iso.8082/OFED_topdir/BUILDROOT/mlnx-ofa_kernel-3.0-OFED.3.0.2.0.0.1.gea32cb7.x86_64/home/ronnie/kernel/initrd_files_compiled/lib/modules/3.12.44-52.10.1.NK_SLES12/updates/compat/mlx_compat.ko': No such file
*** ERROR: same build ID in nonidentical files!
/usr/src/ofa_kernel/default/compat/mlx_compat.ko
and /home/ronnie/kernel/initrd_files_compiled/lib/modules/3.12.4452.10.1.NK/updates/compat/mlx_compat.ko
error: Bad exit status from /var/tmp/rpm-tmp.MHzqCE (%install)
-Ronnie