Which of the following tasks allows for the duplication of custom reporting settings?

The task that allows for the duplication of custom reporting settings is to run the copy custom report task. This functionality is specifically designed to create a duplicate of an existing report, including all its configurations and custom settings. By utilizing this task, users can quickly replicate reports, which is particularly useful for maintaining consistency across similar reports or when making slight modifications to existing reports without starting from scratch.

The other options do not fulfill the same purpose. Exporting custom data involves extracting data from the system but does not directly create a duplicate report or maintain the report's structure and settings. Creating a new report from scratch would require the user to manually set up all parameters and configurations, which is not as efficient as copying an existing report. Merging reports using primary actions pertains to combining data from different reports rather than duplicating report settings individually. Thus, running the copy custom report task is the most efficient and direct method for duplicating custom reporting settings within Workday.