[Enhancement] Silence error when `ManagerMixin` built instance with duplicate name. (#990)

* [Fix]Silence error when ManagerMixin built duplicate name instance

* [Fix]Silence error when ManagerMixin built duplicate name instance

* Update mmengine/utils/manager.py

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

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Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>