CAM-based search engine devices operate to reduce the occurrence of duplicate learned entries within a CAM database when processing search and learn (SNL) instructions. A search engine device may be configured to support processing of first and second immediately consecutive and equivalent SNL instructions as a first SNL instruction and a second search and search instruction, respectively. This processing is performed in order to block an addition of a duplicate learned entry within a database in the search engine device. The search engine device may also be configured to selectively block processing of the second SNL instruction as a second search and search instruction in response to detecting the database as full when the first SNL instruction is processed.