# DuplicateChild (/docs/errors/chain/DuplicateChild)

The children list passed to `set_children` contains the same child hotkey more than once. Deduplicate the `children` argument; current relations are visible in the `ChildKeys` storage for the parent hotkey and netuid.

Declared by the `SubtensorModule` pallet; it classifies to the semantic code [`invalid_argument`](/docs/errors/invalid-argument).

## Remediation [#remediation]

Check the argument values against the operation schema

The same explanation is available in the terminal: `btcli explain DuplicateChild`.