Multiple Anchors
Redundancy that isn't duplication.
Observation
A mussel holds on with many byssal threads, and they are not identical. They differ in angle, length, and stiffness, so a wave that snaps one set loads the others differently rather than equally.
The animal is not attached more strongly. It is attached in more ways.
Pattern
Redundancy of the same kind fails to the same cause. Redundancy of different kinds fails to different causes.
The useful variable seems to be variety of failure mode, not count of components.
Elsewhere
Three suppliers in one region are one supplier under a flood. Three replicas in one availability zone are one replica under a power event.
Personal finances rhyme here too: several income streams that depend on the same client are a single stream wearing a costume.
Question
Could a system be audited not by counting its backups but by listing the distinct events that would remove each one?
What would that list reveal about arrangements that currently look diversified?
Break
Varied attachment costs energy and coordination. Mussels pay that in material; organizations pay it in overhead, and past some point the overhead becomes the fragility.
Diversity of failure mode is not free, and the analogy rarely mentions the bill.
The resemblance is the beginning of the question, not the answer.