How the results look like?
When duplicating an epic, you can easily track the progress as the issues are duplicated step by step. The source issues are shown on the left, with a spinner in the middle indicating an ongoing process and a 
icon once the duplication is finished. On the right side, there is a link to the new issue, allowing you to navigate directly to it (link opens in a new tab).
At the top of the interface, a progress bar indicates the current status of the process. For larger epics, it also shows an estimated time remaining. This estimated time is determined by the duration it took to duplicate each individual issue that has already been completed.
Duplication in progress
When an error arises, it will be denoted by a 
icon, and the corresponding error message will appear on the right-hand side.
Once the process is finished, you can easily access each source or target issue by utilizing the provided links
Duplication completed
If you wish to duplicate the epic once more, simply click the ‘back’ button to restart the process and create a new epic.