Is an admission of ownership valid if the owner is specified vaguely?

Primary text

The declaration, 'I seized it from one of them,' or 'It belongs to one of them,' is valid because an admission concerning an unknown entity is valid, requiring the declarant to clarify the identity. If one person is specified, the property is delivered to him. He must take an oath if the other person claims ownership, but nothing is due to the claimant because the original declarant did not admit owing anything to that claimant.