E006: Duplicate Key

Severity: Warning

duplicate key `name` in binding set

The same key appears more than once in a let block or attribute set. Nix silently allows this (the last definition wins), but it is almost always a mistake.

Common causes

• Copy-paste error where a binding was duplicated.
• Two inherit clauses pulling in the same name.
• A large attrset where the same key was defined in different sections.

How to fix

• Remove the duplicate definition. The diagnostic points to the second occurrence and links to the first.
• If both definitions are intentional (rare), restructure the code so the intent is clear – e.g. use // to explicitly override.