Duplicate --config=foo produces a seemingly pointless warning

As of Bazel 3.2.0, if you have `build --config=foo` in multiple places (like `.bazelrc` and `~/.bazelrc`), `bazel build` produces the following warning:

> WARNING: The following configs were expanded more than once: [foo]. For repeatable flags, repeats are counted twice and may lead to unexpected behavior.

It's not clear under which scenario `--config=foo` may be "repeatable" or produce "unexpected behavior". To my understanding, such a thing cannot happen, and hence the warning seems like a bug. There does not appear to be any conflict in the requested flags. Could the warning be removed?

Start by reproducing the warning with duplicate build --config=foo entries in .bazelrc and ~/.bazelrc, then locate the Bazel code that expands configs and emits this warning. Determine whether duplicate configs can affect repeatable flags, and use the relevant existing tests if found; done means the warning is removed or its behavior and expected handling are clearly established.

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