Md. Code, Commercial Law § 18–302

Except as provided by § 7-601 of this article, a warehouseman or his officer, agent, or employee may not issue or aid in issuing a duplicate or additional negotiable warehouse receipt for any goods:

(1) Without a conspicuous notation on its face of the word “duplicate”;

(2) With knowledge that the original warehouse receipt for the goods is outstanding and uncancelled.