Duplicate object key

What it means

JSON does not forbid duplicate keys, but the result is ambiguous: most parsers keep only the last occurrence and silently discard the earlier values. This is almost always a mistake.

Example

{ "id": 1, "id": 2 }

{ "id": 2 }

How to fix it

Remove or rename the duplicate so each key appears once.

Validate your JSON to see this and every other issue highlighted in one pass.

Diagnostics on this page come from @jsonlint/core, the open-source engine that powers the JSONLint validator. Install it with npm install @jsonlint/core.