The most direct and appropriate method for a marketer to identify duplicate leads based on a field other than the default email address is by creating a Smart List. Within the Smart List, the marketer can use a filter for the "Full Name" field and apply a "has duplicate" constraint. This instructs Marketo to query the database and populate the list with all individuals who share the same value in the "Full Name" field, effectively identifying potential duplicates without altering any system-wide settings.

A. Adjust the duplicate System Smart List filter value to Full Name: The "Possible Duplicates" System Smart List is automatically generated based on the system-wide deduplication key (email address by default) and its filters cannot be modified.

C. Edit duplicate identification settings in the Admin panel: This action changes the fundamental, system-wide unique identifier for the entire Marketo instance. It is a significant architectural change, not a simple identification task, and is generally not recommended for a non-unique field like "Full Name".

D. Create a segment using Full Name: Segmentation is used to group people into distinct audiences for targeted marketing campaigns (e.g., by industry or region), not for identifying records with duplicate field values.

1. Adobe Experience League, Marketo Engage Documentation, "Find Duplicate Leads": This document outlines the process for finding duplicates. It states, "You can find duplicate people based on any field you choose... Create a smart list of people who have duplicates." It then provides a step-by-step guide using a filter (e.g., Email Address) with a "is not empty" operator and a "has duplicate" constraint, confirming this is the correct procedure which can be applied to the "Full Name" field. (See section: "Find Duplicates Based on a Field").

2. Adobe Experience League, Marketo Engage Documentation, "Deduplicate Leads": This document clarifies the system-level functionality. It states, "By default, Marketo Engage uses the Email Address field to identify duplicate people." This confirms that changing the deduplication logic requires an administrative change (Option C), which is distinct from simply identifying duplicates via a Smart List (Option B). (See section: "How Deduplication Works").

3. Adobe Experience League, Marketo Engage Documentation, "Understanding Segmentation": This resource defines the purpose of segmentation. It explains, "A segmentation is a sub-division of your database... Use segmentations to run more targeted and relevant marketing campaigns." This confirms that segmentation (Option D) is a tool for audience grouping, not for data quality tasks like deduplication. (See section: "What is a Segmentation?").