What were you trying to do that didn't work?

The /etc/grub.d/01_users tends to indicate that superusers variable can be multi-valued, hence different user names may be used to authenticate.
The Grub code also tends to indicate this.
However, the current implementation of password_pbkdf2 only supports passing one username exactly.
Is that expected?

What is the impact of this issue to you?

Low impact, just an admin question.

Please provide the package NVR for which the bug is seen:

All Grub releases

How reproducible is this bug?:

N/A