Clone Pipline is used to clone yaml pipeline definitions on Azure DevOps Server 2020+.
This will not clone the yaml file behind the pipeline definition, just the pipeline definition referencing the yaml file, along with all potential options or settings used in the pipeline definition itself (for example variables or triggers which are not defined in the yaml file).
Instructions
Go to the details view of the pipeline definition you want to clone, click on the context menu in the upper right and choose Clone pipeline:
In the appearing dialog enter the path in which to place the new pipeline definition (default will be the same path as original pipeline definition) and the new name of the pipeline definition (default will be the same name as original definition appended by the string "-Copy")