If you need to authorize someone to make a duplicate key, here is a sample template you can use to write an authorization letter for key duplication.
I am, [Name], the registered owner of the undersigned property for which key duplication is required urgently. I hereby authorize my [relation], [Person’s Name], to carry out the key duplication process of my property for me. [He/She] shall proceed on my behalf and take actions that shall be considered of equivalent authority as mine.
For the verification concerns, I have asked the applicant to provide you with [his/her] identity proofs. Kindly cooperate with the same and allow the mentioned applicant to retrieve duplicate keys. In case of further clarifications, feel free to contact me at [Phone Number].