You can safely ignore it.
"These kernel messages should be treated as warning, not error. You should not remove blacklisted hashes (i.e. do not clear secure boot keys), this is a security measure to protect against malicious signatures.
These kernel messages now show because we hardened this security mechanism, and it now reveals issues with some firmwares.
There is an ongoing kernel patch to update this error message: https://lore.kernel.org/lkml/3b997266-0 … gikod.net/"
as reported in source.
This is something that the different manufacturers need to correct in their BIOS/firmware.
The correct approach (of seeing the messages as a Warning instead of an Error) is confirmed in the patch discussion:
"We should not hide EACCES errors. This logs issues, which is correct for duplicate hashes, and can help firmware vendors to fix their database.
I'd really like to see a different log message instead: change the
duplicate entry error code from EACCES to EEXIST, and call pr_warn for
this specific case."
You just need to wait for upgrades from your motherboard producer. (Asus, Dell, Lenovo, etc.)
Or contact their support to report the issue and request a fix.